I don't know, just initial impression stuff:
In the first one the c3 knight is white's worst minor, so leaving him with that would be nice. Also e6 is backwards, and after those trades black can probably force e5 at some point if it's good. So it seems to minimize white's good stuff and minimize black's bad stuff.
In the 2nd one if he totally owns e5, then a pawn will never challenge d4 so this just seems good in general. The comment about kingside superiority is that's where white's pieces are pointed and black's pieces (namely the bishops and queen) aren't doing much there.
Also lifting a rook gives opportunity to swing it over to the kingside to help attack, and while doubled sacs on e6 can be threatened.
Below are two positions from Jacob Aagaard's "Positional Play" along with a statement he made about each position respectively. I'm having trouble understanding him and would appreciate some explanation. Thanks!