There is no chilli. When a product tells you “chilli” in its ingredients, it’s lying. The pictures you see, of shiny red pods, of the glowing powder, of neon yellow habaneros, of green New Mexican peppers – they are not chilli. Not just the way Magritte said that “This is not a pipe,” because it is just a picture of a pipe, but because even an actual plant, or pod, or powder, is not “a chilli.”
It is not that there are too different names and spellings. It is not a chili or a chile pepper or red pepper or any of those labels, either.
What it is, that is a certain variety or cross, or at least a particular species, perhaps grown in a certain area, maybe also processed in distinct ways, and therefore not “a” chilli, but *the* particular chilli it is.
It is, at the very least, an habanero or a New Mexican-type pepper.
It is even more likely, though, an Ancho or Poblano or Mulato or Pasilla or Jalapeño or Chipotle – different in variety, different in whether green or red pods are used, different in whether we talk about the fresh pods or the dried ones, or also smoked pods.
It is a 7 Pot or a 7 Pot Jonah or Douglah, a Kitchen Pepper or a Scotch Bonnet, a Caribbean Red or a Fatalii, a Trinidad Scorpion or a Trinidad Perfumed Pepper.
It is Piment d’Espelette or Pimentón de la Vera or Hungarian Füszerpaprika in one level of pungency or another.
These names might still, also, lie somewhat because they seem to refer to different varieties when, in fact, they refer to pod types. A jalapeño is not the variety jalapeño, but the type jalapeño, the distinct shape of pods and (to a lesser extent, but still) the level and kind of pungency and flavor that goes with it.
It might even be a name that has only just been invented, and it is, often enough, names that say nothing more than how this is (typically used as) green or red chilli or seen as the local chilli or having some typical trait.
Anyways, it is not just “chilli.”
It is not just chilli even because it is not just pungently hot. It is also the different kinds of paprika, of bell peppers, and used in green or ripe stages, at the very least. It is also different flavors and aromas, and it is even different kinds of heat.
A fresh green Serrano is hardly the same as a fresh green Jalapeño; a fresh red Jalapeño hardly the same as a smoked and smoky Jalapeño – which is a Chipotle, after all.
Of course, then, an habanero of whichever kind is not the kind of chilli pepper that a Chinese recipe will call for. Thai Tom Yum Gung will need a fresh chilli of a Thai type harmonizing with the sour flavors of the lemongrass and kaffir lime, the fishiness of the seafood, the requisite level and kind of heat.
Even when sour and spicy and fish goes together well, anyways – just like we also find in the South American ceviche – there will be a kind of South American, slightly fruity-berry, ají in that, not a Thai kind of pepper.
So, experiment all you want, explore and discover – but pay attention to the rich diversity, forget the generic “chilli.”