he plays on the wings in an advanced playmaker role. i.e. can cut inside, play through balls, shoot and can also do the winger thing of run wide and cross. he's very good at all the above.
to compare for clarity, Valencia plays on the wings but in a winger role. i.e. dribble/cross, rinse and repeat. Obviously, any player who plays on the wings in an advanced playmaker role can do it in the center behind the striker but they are more influential on the wings due to more space/less crowding and more options available when taking on defenders.