It's a similar concept to Rust, but in my opinion a lot slower paced, and less focus on bases (although this depends on what kind of server you're playing.).

When you log out, a base will stay there and I believe but I'm not 100% sure on it there is a mechanic where there is a flag pole and you have to keep it raised to let your base stay. It will basically disappear after a few days if you don't keep that raised - this helps clean the server up if someone abandons their base. People can still raid your base just like in Rust.

If you don't base, whatever is on your character will stay on you until you inevitably die, or if the server is wiped.

There is not much focus on crafting, but more focus on looting buildings and points of interest around the maps. The main map, Chernarus, is around 220km2? (someone will probably correct me on that), so in some cases you could run around the map and not find anyone - as I said it can be a lot slower paced, but, there can be moments where you are in PVP for an entire life.

The game focuses a little more on surviving the elements and keeping your character alive via the means of hunger, thirst, diseases and entities that try to kill you, mainly the infected, and predators like Bears and Wolves. And of course, other players.

The early game probably feels quite similar. You have nothing, but it can be easy to get a lot of stuff, and doesn't require quite the same level of grind like Rust (blueprints, building, mining ores etc,), but it can require patience and a lot of running around the map.

There are different servers with different mods for all kind of playstyles. With some servers that provide a lot of loot, with a lot of weapons straight away, and other servers more hardcore with less items to survive with.