Append vs. Join?

Hi Datawatchers -

I'm fairly new to Monarch and the DPS, but so far I'm really enjoying it. That said, can anyone explain (in as simple terms as possible) the difference between creating an append versus a join in Data Prep Studio? I'm mostly confused with how the append function works, as well as how this is different than creating an append template in report design. If able, can you please provide a scenario where an append would be more appropriate than join? Any insight/explanation is greatly appreciated!

CD