Samsung, locked in a tight race with Apple to be the world's biggest smartphone maker, has unveiled an important new phone that ditches its signature plastic design for more stylish metal and glass.

The South Korean phone manufacturer also unveiled a premium model with a display that curves around the left and right edges so that information can be glanced at on the side.

The Galaxy S6 and S6 Edge will both include technology for mobile payments, though Samsung isn't unveiling a service to rival the iPhone's Apple Pay until this summer.

Samsung and Apple have gone back and forth as the world's top smartphone maker in recent years. Apple's iPhone 6 and 6 Plus, released last year, have helped the Cupertino, California, company catch up. Both of Apple's new phones are larger than previous versions and their size was heavily marketed, in part to appeal to customers who liked Samsung's large phones.

Now Samsung's S6 phones will have a metal frame - like the iPhone. The phones also have a glass back, which Apple abandoned in favor of metal in recent iPhones.