Well my server is running on a latest steam thingie. What dproto simply does? It makes it possible for p48/p47 users to connect. Well that is simply as far as I know.
Nonsteam servers are different yeah, they run on a total nonsteam, no dproto used. There are different server clients for nonsteam, but dproto is simply a MetaMod plugin, which makes it possible for p47/p48 users to connect.