ROBLOX is very much indeed different than Minecraft. ROBLOX is a platform, not a game, it offers games that are created by users. Meanwhile Minecraft is a game as you have one world to work with, servers offer some more fun as you get to play with other players and play certain mini-games and such. ROBLOX, you can play with others but you need to find the right place to play at. ROBLOX is free-to-play, just go to their website, download the installer, find a game you want to play and click the green “play” button. You need to buy Minecraft in order to play, but it offers different possibilities as you get to survive and mine and do whatever you want. Anyways, that should clear up any confusion.