Robinhood is an app that lets you trade, it's all real trading on the same market as everyone else, it's just an app allowing you access. WallStreetBets is just a community of "investors" who trade on real markets, but with Robinhood having such a low barrier to entry they often trade using it. (Screenshots of Robinhood trades going really well or really badly are a staple of WallStreetBets humour).