What is the flavor difference between grape and cherry tomatoes? The store had both and they looked rather similar.
The difference in their name is - not surprisingly - because of their form. Cherry tomatoes are round, while grape tomatoes are more oblong. Wikipedia mentions that grape tomatoes are 'sweet as cherry tomatoes', so not much difference in flavour according to this. Perhaps grape tomatoes are more similar to small plum tomatoes.
This site claims grape tomatoes to be sweeter, having a thicker skin and a lower water content than cherry tomatoes. Interestingly, it also says that grape tomatoes are a cross between cherry tomatoes and other tomatoes.
The claims of the second site are in agreement with this site ("grape tomatoes have thicker skin, lower water content and intense sweetness"). It also states "a grape tomato is half the size of a cherry tomato", so perhaps they are smaller. Due to the lower water content, grape tomatoes have less chance of 'squirting' when being bitten into.
If there is a difference, I think it's smaller than all of the normal variations in supermarket tomatoes. Buying either kind, I've gotten plump/juicy ones, drier/mealy ones, sweet ones, bland ones. I think this is mostly attributable to the wide variation in quality of storebought tomatoes, notably seasonal variation and how unripe they were when picked. Some may actually be different types of tomatoes, too: I know there are a few reasonably widespread cultivars sold as cherry tomatoes.
I think the primary reason for the "grape" name is just the shape; cherries are more spherical and grapes are oblong. Both grape and cherry tomatoes should usually be sweeter than larger tomatoes.
If you're a gardener or are lucky enough to know someone who can supply you, I think you'll find much more variety in flavor among all the types of little tomatoes that people grow at home. I've had some that were so sweet I felt like I was eating delicious tomato candy off a vine, and I've had others with a full tomato flavor but not so much sweetness. Unfortunately I don't know names of varieties here, but I'm sure if you sought out that sort of thing, you could discover the ones you like most!
Cherry Tomatoes depending on variety are usually more tangy than sweet. A popular variety sold in Australia is Genio (unsure spelling) has a long shelf life with tangy flavor. Suitable for salads as a replacement for tomatoes. They also tend to hold their shape better during cooking compared to the run of the mill variety of grape tomatoes.
Whilst grape tomatoes generally have a sweeter flavor over their cherry counterparts. These usually have a shorter shelf life but ripen quicker as a result. In terms of cooking, grape tomatoes usually have a stronger flavor and may over power other ingredients.
Lastly another issue is when the fruit is harvested. For commercial production cherry and grape tomatoes are typically harvested when they are light orange in colour. With cherry tomatoes some varieties will be sugary sweet if left on the vine until full colour.
Overall, the main issue is identifying which variety is being sold.
Cherry = Tangy
Grape = Sweet
Renaming was inevitable once 'cherry' size became golfballs...
Round or oblong 'grape' tomato? I tried a nice golden egg-shaped wee one; more a texture difference than flavor: crispy juicy rather than mealy squishy.
Blessedly more variety these days in tomatoes. How about pulling aside your supermarket green-grocer and asking for a sample? Not possible with prepackaged punnets but why shop where you can't touch and smell, hmmm?