head to head
LEGO Battles asks more than Overlord, and the gap is reads.

Optimization · Pure Optimization
A simplified RTS testing basic build-order economy with light multiplayer prediction.

Optimization · Practiced Mastery
A darkly comic action game where you herd colour-coded minion hordes as an evil overlord.
LEGO Battles leans Optimization (Pure Optimization); Overlord leans Optimization (Practiced Mastery).
Overlord leans a little harder on execution, though the gap is small.
LEGO Battles
Stylus micro on DS is gentle, not twitch-defining
Overlord
Sweeping minion hordes takes modest dexterity
LEGO Battles leans clearly harder on reads.
LEGO Battles
Multiplayer skirmishes add light human prediction
Overlord
Scripted heroes and creatures
LEGO Battles leans a little harder on variance, though the gap is small.
LEGO Battles
Map fog and treasure hunts hide modest information
Overlord
Fixed level design
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
LEGO Battles
Build orders and base economy decide simplified RTS matches
Overlord
Minion type usage and upgrade economy reward planning
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.