This post is an attempt to keep track of the terms that differ between dialects of English or exist in some dialects but not others: British / Australian / Canadian / American / etc.
It's a community wiki, so feel free to edit and clarify or add additional items. The comments are getting long, so use answers for discussion of specific concepts if necessary, especially if you're not sure what a term means.
- eggplant (US, AU) is an aubergine (UK)
- zucchini (US, AU) is a courgette (UK) when harvested young or a marrow (UK) when allowed to mature further.
- summer squash (US) are members of the squash family with a short storage life that are typically harvested before full maturity; typically available starting in the spring and summer; includes zucchini, yellow and crookneck squash
- winter squash (US) are members of the squash family that are allowed to reach full maturity before harvesting; typically available in the fall; includes pumpkin, acorn and butternut squash,
- arugula (US) is rocket (UK, AU)
- rutabaga (US) is swede (UK) but also called turnip or neep in some parts of the UK, particularly Scotland. (Wikipedia)
- endive (US) is chicory (Belgium, perhaps others)
- capsicum (US, AU) / bell pepper (US) is a pepper (UK)
- seaweed (US) has many names based on type of plant, including Kombu (Japan), Nori (Japan), Laver (Wales), and many others. See (edible seaweed)
- snow peas (US, AU) are mange tout (UK) (word borrowed from French). Mange tout (UK) translated to 'eat everything' and also includes sugar snap peas (US).
- peanuts (US) may be calledgroundnuts in the UK, particularly in reference to the oil (peanut oil (US) vs. groundnut oil (UK))
- legumes (US) are pulses (UK). 'Legume' may refer to the plant and not the seeds (lentils, beans, etc)
- mealy potatoes (US) are floury potatoes (UK). This refers to high starch, low moisture potatoes that result in them softening significantly when cooked (useful for mashed potatoes or using for thickening; the opposite of waxy potatoes)
Herbs, Spices & Seasonings :
- kosher salt (US) is flake salt (UK). Some sea salts may be appropriate substitutes (ref)
- coriander (UK) tends to refer to the leaf (cilantro in the US), unless qualified as 'coriander seed'. May be qualified as 'fresh coriander' or 'green coriander'. 'Ground coriander' is always the seed.
- coriander (US) refers to the seed
- cookies (US, CA) are biscuits (UK, AU, NZ)
- biscuits (UK, AU) also refers to digestive biscuits, which are cookie shaped but more similar to a sweet cracker like the graham cracker (US, CA)
- biscuits (US, CA) are similar to a scone (UK, AU), and usually neither sweet nor savoury
- bisquit (Germany, no plural) is sponge cake (US)
- muffin (US, AU) is a quick bread (typically using the 'muffin method') baked in forms used for cupcakes. It increasingly has this meaning the UK too, with the prevalence of American-style coffee-shop chains.
- muffin (UK) is english muffin (US, AU), a yeast leavened flat-ish bread, cooked on a griddle with a ring form.
- scone (US, CA) tends to be sweeter than a scone (UK)
- pancake (US, CA) generally refers to puffy item made from a thick leavened batter
- pancake (US) can also be called hotcakes, griddlecakes, or flapjacks
- pancake (UK) are made from a thinner unleavened batter, with a result a little thicker than a french crêpe.
- drop scone (UK) is similar to a (US, CA) pancake
- flapjack (US) is the same thing as a pancake
- flapjack (UK) is a baked square usually consisting of sugar/honey, butter, and oats
- frosting (US) is icing (UK, CA, AU)
- frosting (US) typically has air whipped into it, while icing (US) doesn't and dries harder
- turnovers (US) and hand pies (US) are pasties (UK). Pasties (US) are coverings to comply with nudity laws in strip clubs.
- ground beef (US) is minced beef (AU, UK)
- Canadian bacon (US) is also back bacon (from the loin)
- bacon (CA, US) is streaky bacon (UK) (from the belly)
- bacon (UK) unless qualified is most likely back bacon.
- pork rinds (US) are scratchings (UK, when dry) and crackling (AU,NZ & UK when fresh from a roast).
- names of cuts of meat in the US may differ from other countries. See wikipedia for images of US and British names of regions
- single cream (UK) = cream with 5% butterfat
- double cream (UK) = cream with 48% butterfat
- half-and-half (US) = a mix of half cream, half milk (about 12.5% butterfat)
- light cream (US) = cream with 18 to 30% fat
- light cream (CA) = cream with 5 to 6% fat
- whipping cream (US) = cream with 30 to 36% fat
- heavy cream (US) aka heavy whipping cream (US) = cream with more than 36% fat
- whipping cream (CA) = cream with 35% milk fat
- table cream (CA) = cream with 18% milk fat
- buttermilk (US, modern usage, aka 'cultured buttermilk') is a fermented product, basically a runny yogurt.
- buttermilk (US, historical usage) is the liquid left over after churning butter, which when fresh is closer to skim milk.
- sour cream (US) = soured cream (UK)
- powdered sugar or confectioners sugar (US) is icing sugar (UK, CA); contains cornstarch (~3%) as an anti-clumping agent.
- superfine sugar (US, CA) is caster sugar (UK, NZ, AU); may also be called berry sugar (CA), fruit sugar (CA), bar sugar, castor sugar, instant dissolving sugar, ultrafine sugar, fondant sugar, extra fine sugar.
- sanding sugar (US) is pearl sugar (CA). (size between coarse sugar & granulated sugar)
- unless otherwise qualified, sugar (US, CA) is granulated sugar
Other Food / Ingredients:
- dessert (US, AU) is pudding, sweet, dessert or afters (UK, depending on region and social class)
- pudding (US) is roughly equiv. to custard (UK)
- jello (US; brand name issues) is jelly (UK, AU)
- jelly (US) is seedless jam (UK) (see answer below for details)
- fries (US, abbr. for french fries) are chips (UK); both terms work in AU
- chips (UK) are steak fries (US)
- chips (US, AU) are crisps (UK)
- cornstarch (US) is cornflour (UK)
- corn flour (US; aka masa harina/fine corn meal) is cornflour (UK)
- cider (US) is unfiltered (cloudy) juice, commonly from apples, while cider (UK) is an alcoholic beverage made from apple juice (aka. hard cider (US) or scrumpy (UK) for stronger dry ciders)
- all-purpose flour (US) is plain flour (UK)
- liquid smoke (US) is condensed smoke, used as a flavoring.
- black beer (UK) is a malt liquor/fortified wine containing malt.
- black beer (US, Germany), also called black lager or schwarzbier is a type of lager brewed with extremely dark malt.
- tomato sauce (UK) is ketchup (US). Also catsup and other spelling variants.
- tomato sauce (US) is a tomato based sauce typically for pasta or pizza.
- marinara (US) is used synonymously with tomato sauce, and may refer to both quick or long-cooked varieties.
- tomato paste (US) is tomato purée (UK)
- tomato purée (US) is unreduced tomatoes (possibly stewed) with the skin and seeds removed. Also called crushed tomatoes.
- tomato passata (UK) (sometimes just 'passatad') is strained tomato purée (US).
- broiling (US) is grilling (AU, UK)
- grilling (US) is barbecuing (AU)
- barbecuing (US) is slow cooking using wood or charcoal to impart smoke to the food
Tools / Equipment / Non-food items :
- parchment paper (US, CA) is greaseproof paper (Ireland/ UK, NZ)
- stove (US, CA) is also range (US, CA) and hob (UK)
- crock pot (US; brand name issues) is a slow cooker (US,UK). Also slo-cooker (UK; brand name issues)
- food processor (US, CA) is sometimes a magimix (UK; brand name issues)
- canned items (US) are tinned (UK)
- recipe (US) is sometimes called a receipt in other areas and in older usage (pre-20th century).
- receipt (US, modern usage) is "a written acknowledgment of having received a specified amount of money, goods, etc."
- aluminum foil (US), aluminium foil (UK) is often referred to as tinfoil (US, UK), which had previously been in use for similar purposes.
- plastic wrap (US), cling film (UK) is often referred to as Saran™ wrap (US brand name) or Glad™ wrap (NZ, AU brand name)
Units of measurement :
- teaspoon (US,UK, CA) is 5 mL (note: abbreviated 't' or 'tsp')
- dessert spoon (UK) is 10 mL
- tablespoon (US,UK, CA) is 15 mL (note: abbreviated 'T', 'TB', or 'tbsp') (20 mL in AU)
- A "stick" of butter (US) is 1/4 lb (113 g); the physical stick is marked into eight "tablespoon" divisions [slightly larger than an actual tablespoon]
- A "cup" (US) is a fixed measure of ~236mL (8 fluid ounces, 16 TB, 1/2 a US pint); in AU, CA a "cup" is 250mL.
- Equipment for making tea or coffee may base their 'cup' count on 6 oz. teacups. Please look for information in mL or L when buying kettles or similar.