This can be confusing - it's not entirely consistent naming.
I'm sure you've read else where and even on this site "don't worry if it's holes or electrons - the convention is positive charge flowing from a positive voltage to a more negative voltage to define +'ve current flow"
" a negative charge flowing in the opposite direction equals positive current flow - the two signs cancel and you end up with positive charge flowing in a positive direction"
Then why does a nfet have a source that is on the -'ve rail and a drain that is at higher voltage? after all the "source" should be considered the the circuits above it "sourcing positive current and it drains the positive current into the drain. It would be consistent then.
So the short answer is, all those saying are true with respect to current, but device polarity is important to functionality and manufacturing. If you are connecting complementary polarity devices (P & N) in the same substrate you DO need to think about whether the device works with Electrons or with Holes or you'll mess up.
The easiest way to remember this is: