Yes. a Magazine is the same thing as a Community on Lemmy and a subreddit on Reddit hence the r/whatever on reddit, m/whatever on KBin and c/whatever on Lemmy.
An instance is the name given to a server thats installed and run a copy of the KBin (or Lemmy) software. So kbin.social is a different server than fedia.io - both are running the KBin software but on different servers. You can create communities on one or both which can lead to overlap - there are several c/funny communities on Lemmy for example, each on a different server, modded by different users.