Nova was a hexed client from i think 10.0 to 11.1 and ninjin was made from 11.1, so if it were me, I would rather ninjin's, otherwise certain things in game would be missing from view using a hexed version e.g. rock dragon. If its mods you are after, then yes they are practically the same. I only say nova is hexed because i have checked both clients against Jnoobs source codes, and the nova client does not match any of Jnoobs codes, folders, or file names, where as ninjins does.