No, it's that easy either, because Russia has way more losses than Ukraine. You also cannot just look at raw population numbers like it is a video game where every number represents a potential soldier. There's people who aren't able to fight, there's also people with critical jobs to keep the economy afloat, or even just society or basic infrastructure. Those losses are very significant and will affect Russia for a very long time, hence why Putin called for women to become breeders for the motherland.