fel?z d?a del amor y de la amistad
The difference is that everyone congratulates each other on Feb 14th because it's celebrated as the day of friendship as well as love.
Although Valentines cards are on sale they are not as central to the day as in Europe and N. America.
The similarity is the commercial exploitation of the occasion: a lot of businesses find a way of cashing in. Street vendors sell flowers at traffic lights, restaurants have special Valentine's Day menus.
Hope you all had a happy one!
Chiri