Account Hub is experimental and only gets used when you have at least one account already created in Thunderbird.

Both Account Hub and Account Setup can be used for imap and pop accounts.

I see now there are confusingly two different user interfaces to ad accounts to thunderbird. I cannot say that this is reassuring for new and old users. Certainly with something so critical as setting up accounts.

and yes, asked a similar question as these two user interfaces are different.

This confusing "feature" can be shut off in settings (click top left hamburger)