Well, the biggest difference is that, unless things have changed, OSX Server requires that you use UFS instead of HFS+, and that's caused me problems in the past. I don't now remember exactly what those problems are (good story, grandpa), but I remember having to reinstall in order to get rid of UFS and fix them.

This is not to denigrate UFS, It's a better filesystem, IMO, but there were so many things that Mac programs wanted to see that were HFS+-specific.