Hello there! Leveling is the same. Fates, Dungeons, etc. There are also new little things that can help you get extra exp like weekly challenges, hunts, etc. Population, depending on the servers, but I think most serverd are quite active, I can only vouch for Ultros, still active. As for leveling a new clas, I would go with the same character, but thats all preferences imo.

If interedted, I have an FC in Ultros that help with story content instances, so you can clear them asap, and enjoy the high level events smoothly : )