Quick Play: Get matched with random players from around the world. You get to vote on one of two maps chosen randomly from the map pool.
Friends Play: Create a game session and invite your friends to play. You can either select a map to play with your friends, or choose Quick Play to fill the game up with random players.
2 vs 2: Team up with one of your friends and beat two random players. You and your partner's rating will be shared between you. If you and your partner are in the same clan you will receive bonus points at the end of the race.
Practice: Offline playing versus bots. You get no coins/rating, but it's a nice way to prepare your winning strikes against your friends or random players. You can find Practice mode in the upper left corner of the Play screen: