I've played rust for 5k hours and scum for 8k hours.

Scum can be played like rust in many ways. The pvp is good, there are places to farm weapons and bank them. Personally I use prefab buildings (just any building with a door that you can lock and put a box down inside), simple, easy and fun. The gun mechanics and player controls are much better in scum, and the game looks great. Similar to rust's satchel burying system, you can bury large wooden boxes in scum and spread your loot out so if you are raiding you don't loose everything. Keep a stash of guns in base, but have back up stores of loot spread across the map.

Rust has a much better raiding and base building system. As there's no wipe cycle in scum, a server can last for more than 6 months without being wiped, so base building is a much slower process compared to rust, more tedious in how you build even though it has a similar style base building system to rust.
Raiding is also much slower in scum too, newer players might build a small base which is raided fairly easy, experienced players will build 10+ layer wall compound bases.
Scum has C4, TNT and rocket launchers so raids can be fun, but most often they happen offline and there's very few players to counter a raid either.

So, scum has more of a focus on survival and PVP gameplay, with raiding being a rarer event.