Russian army is an eastern army so its more cavalry focused, infantry is less important on the vast steppes. To travel across these lands, one needs a horse, so warriors on horses are more practical. I like Russians for they cavalry: Boyars, Druzhinas, HA, Heavy Steppies, Mounted X-bows. This is just a different type of warfare compared to catholic factions. The difference doesnt mean Russian forces are weaker, they are just different, and of course very effective.

Regards,
EC