Ken Masters is a fighter from USA whom was sent by his father to master Gouken. There he trained under his Gouken along with Ryu under a fighting style called
Ansatsuken. Ken's primary focus is on the Shoryuu principle which is why his Shoryuken move is characterized with flame while Ryu follows the Hadou principle.
The difference between the Ansatsuken twins is mainly in their moves. Ken has a stronger Shoryuken and multi-hitting Tatsumaki Senpuukyaku(
Hurricane Kick) while Ryu as a single hit knockdown
Hurricane kick and a stronger and faster Hadoken.