In Starcraft 1 terms:

Ukraine is playing protoss but for some reason is only using very few scouts for air combat

Russia is playing terran more or less in a balanced attack force but is using siege tanks alot because they know they’ll be able to outrange them in ground combat.

to make matters more interesting, the terran Russia already built an army and has all of the resoureces they need before the war started. The protoss Ukrainians don’t have enough resources and the way that they build units are expensive as it is.