head to head
Neither is simply harder - they are hard in different places. Peggle demands more execution; UNO demands more reads.

Variance · Pure Chaos
Pachinko-puzzle hybrid where one lucky bounce triggers Ode to Joy.

Variance · Pure Chaos
The classic shedding card game where the deck, not the player, usually decides.
Peggle leans Variance (Pure Chaos); UNO leans Variance (Pure Chaos).
Peggle leans clearly harder on execution.
Peggle
Aiming the launcher is gentle
UNO
Playing a card requires no dexterity
UNO leans clearly harder on reads.
Peggle
No opposition whatsoever
UNO
Mild bluffing about held colors and wilds
UNO leans clearly harder on variance.
Peggle
Bounce physics chaos decides most shots
UNO
Hidden hands and the draw pile decide most games
Peggle leans a little harder on optimization, though the gap is small.
Peggle
Angle planning and power choice for setups
UNO
Basic card-retention strategy caps out quickly
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.