aramis erak
Legend
So everything is either a one-shot or an adventure path? By that standard, almost every adventure ever published is an adventure path, which makes the definition useless. I never heard of anyone playing through e.g. Keep on the Borderlands or Palace of the Silver Princess in a single session, so by your definition they are adventure paths too.
Adventure paths don't have to take you from 1 to 20, but they should be the basis of an entire campaign, starting at low levels and taking you to very high ones. They should have multiple distinct phases. Something like Dragon's Demand is just a regular adventure. I'm personally not happy calling Princes of the Apocalypse an adventure path either, because I do not think it has the required sequentiality to it. It's just a big adventure.
A sequence is two or mor modules where all but the first one are a sequels to a prior one.
A path is a sequence where the intent is to go straight from A to B (to C) etc., without diverting to a non-sequence member.
A path can also be an omnibus where many chunks could be done as standalone modules, but for which the intent is a single super-module.
HotDQ is easily so. GDQ is. ToEE and RttToEE are not - Return is not intended to be a direct follow on. PotA is, even tho it can be taken out of sequence if needs be.