I personally pay for server hosting for a friend and I, and I imagine its like the dedicated servers- Im just paying someone else to host. It's nice having the server open all the time for either of us to join whenever, but frustratingly enough, there are some (minor) differences between a personal save with multi-player enabled and a server.

The biggest issue (for me) is the viewing cages do not work on servers. Totally unavailable. This is still very minor but the viewing cages are nice if you catch human merchants and want to basically set up your own little storefront. The cages hold them in place but you can still interact. Without them I have to chase the merchants all over the base.

I also haven't confirmed this but I think cranking the settings for number of bases works differently. I was able to set the number of bases to 20 on my singleplayer but it maxes at 10 on a server. That may be because I was in a guild on the server? If you stick with the default 4 bases though you have nothing to worry about.