Someone will come along and do a far better job but here's the SS: 4chan is a picture messaging board with different channels for different topics. Its anonymous (no user names) and theres no upvoting. Each post becomes it's own thread.  8chan came about as a more political, less censored version as many topics were being banned from halfchan (4chan) ie pizzagate #gamergate ect.  8chan is the anon battle ground.