Martinez said: "Charles is someone who can stop and start. His real talent was the speed he had with the ball.
"Albert is completely different. He stretches teams with his pace but without the ball he gets in great positions. And he is a real crosser of the ball. I wouldn't expect him to play on the right-hand side, he is more of a left winger.
"Both of them are left-footed but completely different. Charlie would prefer to come inside on his left foot and use his quality on the ball, but Albert is more of a provider than Charles.
"He is an exciting player to watch. I think the fans will love him because he is really quick, he is intelligent and the way he plays is completely different than Charles but he can have just as big effect in games.
"I'm excited with Albert. He brings a completely different tactical knowledge into the squad and has experience in La Liga.
"He is going to get the fans really excited. He is someone who can make something out of nothing.''