head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Optimization · Practiced Mastery
Planning a raid in advance, then executing it where one mistake kills.

Optimization · Practiced Mastery
Mastering samurai unit cohesion and clan-specific economic chains across feudal Japan.
Tom Clancy's Rainbow Six leans Optimization (Practiced Mastery); Total War: Shogun 2 leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Tom Clancy's Rainbow Six
One bullet kills, so entries demand clean aim
Total War: Shogun 2
Samurai unit micro, zen arts timing, and castle sieges reward sharp play
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Tom Clancy's Rainbow Six
Multiplayer raids add human counterplay
Total War: Shogun 2
AI daimyo follow scripted clan doctrines; human opponents require reads
Total War: Shogun 2 leans a little harder on variance, though the gap is small.
Tom Clancy's Rainbow Six
Terrorist placements are unknown until doors open
Total War: Shogun 2
Metsuke agent skill rolls and random farm yields add moderate unknowns
Total War: Shogun 2 leans a little harder on optimization, though the gap is small.
Tom Clancy's Rainbow Six
The pre-mission planning phase is the real game
Total War: Shogun 2
Clan-specific mastery paths and trade port chains are the core solvable layer
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.