So whenever I join my friend's game, I notice that our worlds look completely different. I can walk on water, trees appear to be on water, etc. The world that is generated on my friend's computer, is very different from the world that is appearing on mine. Not only that, but I also have lag issues (even though we live in the same house and use the same internet). Any help or advise on this would be much appreciated. Thanks!
P.S. I've attached a screenshot of what it looks like.
Playing the game, trying to figure out if there were any server issues. Has been occuring for quite a while.