Head to head
Which one will break you first?
Two fingerprints on one grid. Both are scored through your profile, so this answers the question for you rather than for the average player.
Rain World is the harder of the two for you, by 1.5 points. The gap is widest on punishment, where Rain World asks considerably more than Age of Empires II: Definitive Edition. If you want the gentler run, start with Age of Empires II: Definitive Edition.
Axis by axis, biggest gap first
RAIN WORLD
A simulated ecosystem that has no interest in being fair. Movement takes twenty hours to feel deliberate, the rain cycle takes back anything you did not bank, and nothing is explained at any point.
The game is the antagonist. Good luck.
AGE OF EMPIRES II: DEFINITIVE EDITION
Build orders are the curve, and the campaigns teach almost none of what the game actually asks for. The hard AI does not forget its economy while it fights.
Sustained pressure. Progress is earned.