Just as important, nobody actually studying algorithms (where having this misconceptions would matter) actually has these misconceptions. It's completely fine for Big-O to mean one thing when chatting with a bunch of devs and another when sitting down for research.
The distinction between all the Big/Small letters is only really useful if you're trying to prove the bounds and something and proving an upper or lower bound is an easier place to start. Honestly practicing programmers shouldn't even be worried about these type of concerns since in practice there are some very small Ns and very large Cs that can make 2^n surprisingly workable and n surprisingly slow. Speaking in rough terms of 'it grows like this' is just fine.
The distinction between all the Big/Small letters is only really useful if you're trying to prove the bounds and something and proving an upper or lower bound is an easier place to start. Honestly practicing programmers shouldn't even be worried about these type of concerns since in practice there are some very small Ns and very large Cs that can make 2^n surprisingly workable and n surprisingly slow. Speaking in rough terms of 'it grows like this' is just fine.