head to head
Peggle asks more than Marbles on Stream, and the gap is optimization.

Variance · Pure Chaos
Tests nothing but luck - a spectator marble race decided entirely by physics RNG.

Variance · Pure Chaos
Pachinko-puzzle hybrid where one lucky bounce triggers Ode to Joy.
Marbles on Stream leans Variance (Pure Chaos); Peggle leans Variance (Pure Chaos).
Peggle leans clearly harder on execution.
Marbles on Stream
You watch a marble roll; no inputs matter
Peggle
Aiming the launcher is gentle
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Marbles on Stream
No opponent decisions exist to predict
Peggle
No opposition whatsoever
Peggle leans a little harder on variance, though the gap is small.
Marbles on Stream
Physics RNG decides the entire race outcome
Peggle
Bounce physics chaos decides most shots
Peggle leans clearly harder on optimization.
Marbles on Stream
Nothing to solve beyond picking a marble skin
Peggle
Angle planning and power choice for setups
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.