Both games are played with cards that have different fronts and backs - letters in the case of Patchword, and designs in the case of Patchwork. In both games, players make sets (or spell words) by swapping, flipping, and trading cards. The following videos feature an interview with Dan about how the games were developed, and then how to play each game.
You can purchase Patchwork and Patchword at PlayFair Toys.
Here's how to play Patchwork: