Not yet castrated males and females are more active and more restless than their neutered counterparts.  Often  there also is a bit of competition between the not nutered cats ..
Neuters ensure in general that there is more peace and stability within the group. This certainly applies to a castrated male. Of course there are plenty of exceptions (each cat has a different character), but in general this is the case. Currently  there are two neuters living  within the Clan. One female and one male.