I’m confused about the distinction (if any) between hazelnuts and filberts. I’m interested primarily as a cook and shopper, but trying to look up the difference led down a deeper rabbithole than I expected, involving not just culinary but also linguistic and botanical aspects.
On the one hand, looking plenty of sources (first of all Wikipedia) draw distinctions between them. From that WP article, for instance:
The hazelnut is the fruit of the hazel tree and therefore includes any of the nuts deriving from species of the genus Corylus […] They are also known as cobnuts or filberts according to species.
A hazelnut cob is roughly spherical to oval […] while a filbert is more elongated.
On the other hand, different sources seem to make the distinction differently, or elide it altogether. Between the two wikipedia quotes above, for instance, the latter distinguishes hazelnut cobs from filberts, while the former presents filberts as a subclass of hazelnuts. And the Wiki article for the species Corylus maxima says:
In Oregon, "filbert" is used for commercial hazelnuts in general. Use in this manner has faded partly due to the efforts of Oregon's hazelnut growers to brand their product to better appeal to global markets and avoid confusion.
And in colloquial usage, I’m unsure if most people make any distinction at all, or if it’s just regional variation. In British usage, I’ve only come across hazelnut in everyday usage (including product labelling), never filbert. From the US I certainly recall hearing both used, including people using filbert colloquially to describe products sold as hazelnuts; I don’t recall if I saw products officially labelled as filbert. So I had assumed filbert was just a US-specific synonym of hazelnut, until reading some sources recently noting a technical distinction.
Overall it seems clear that at least within some specialist circles, there is a distinction, but on the other hand that usage varies, and colloquially at least some people treat them as synonymous. So I’m trying to work out where the situation lies, between “a clear widely-agreed-on distinction, although some non-specialists are ignorant of it” and “mostly used interchangeably depending on dialect; occasionally distinguished in some specialist contexts, but not consistently”. Specifically:
Among people who make a distinction, do they agree on what the distinction is, or do people mean different things by it in different regions/industries/etc?
Is the distinction respected in formal usage — for instance, in food product labelling in the US or UK?
How widely, if at all, do non-specialists make any distinction? In the US, for instance, do most people mean different things by the two words, or just use one or the other depending on their region/dialect? When I see filberts/hazelnuts in a recipe, should I consider them synonyms, or presume the writer intended one specific kind?
