This is a question not about home cooking, but about working out how an industrial food is cooked — I’m not a regular here, so apologies if it’s judged as off-topic.
Extruded snack seems to be the technical term for manufactured not-quite-chips snacks like Cheetos, Cheese Puffs, Wotsits, Twisties, Cheezels… It comes from the way they’re manufactured, by extrusion from a press. It may also involve other technical details beyond this, I’m not sure.
(Twiglets are rather love-it-or-hate-it, flavoured with yeast extract, so a bit like Marmite, except that even people who love Marmite may hate Twiglets.)
Carried over from this english.se discussion.