Good old normal Infinity! This is the server that is the most featured and developed at this stage, but also the easiest of the two. If you've played Infinity before, this is the Infinity you know.
The new kid in town, expert mode. It definitely lives up to its name. Everything is 10x harder to get, however a lot more rewarding and, in my opinion, somewhat more realistic. Most recipes have changed and there's now a progression tree to follow instead of randomly doing mod after mod.