Nice question as far as it goes.
But it would have been nice to go a bit further and have a few more backup types, a list like
Differential database backup
Differential partial backup
Differential file backup
(plus of course incremental backup and maybe more spurious ones)
so that it's clear that the Database/Partial/File distinction is orthogonal to the Full/Differential distinction, giving 6 possibilities plus the log backup to make 7.
And then does WITH Copy Only introduce some more types and if so how many - but maybe that could be a separate QotD.