The only similarities (excluding the fact that they're both FPS games) is that they're both made by the same company in the same engine. CS is more realistic so if you fire your gun while moving it's accuracy is severely decreased. You also have to buy your equipment at the start of the round with cash you earn round to round.
There are also many mods in servers just like TF2. Surf, zombies, gun game, etc.
My best advice is to just play the game and see for yourself.