They’re different words for the same thing: GM, Dungeon Master, DM, Keeper, Referee, MC, Director, Game Master. Whatever name you use, this person sets the stage and manages the flow of the game. While it may seem daunting, you can become a game master.
It’s not easy at first, but it’s also tremendously rewarding. Talk to any long-time game master and they’ll tell you when they first started running games they didn’t know what they were doing – and they still had a blast. Just remember that the point is for everyone at the table to have fun, and you’ll do fine.