currently have win 8/64 bit/pc

Someone pointed out to me that 8.1 is an 'update' of win 8 and not an 'upgrade'..''just an update that happens to take longer ...the 'reminder-banner' i get frequently states
(1) one can 'continue to work' on one's computer while 8.1 is being dowloaded;
(2) no mention to disable AV & firewall (unless that notification pops-up once download begins
(3) why so many problems posted for 'final product' of 8. 1 that i read about for this 'update' when it was in fact part of Windows updates that could have occurred when one has 'auto-install' activated;
and that no Product Key is required for 'activation' or ability to boot=up computer and sign-in.
Please clue me in on all of this ... i'm baffled.