Trying to understand something from my 2021 Lincoln Aviator owner’s manual: What is the difference between (1) Transfer case fluid, (2) PTU fluid, and (3) Front and rear differential fluid?

I always try to follow the manual. Manual states 1 + 2 @ 30k miles. Manual also states 3 @ 45k miles.

I’m at 34k and am planning on doing both 1 and 2 but are they the same thing in an AWD vehicle?