Gerard Butler Vs. Javier Bardem

I know i have got these two confused many times when watching there movies,but it doesn't take long to tell the difference.

Gerard Butler (300, The ugly truth, Bounty Hunter)
http://www.imdb.com/name/nm0124930/

Javier Bardem (Jamon' Jamon', Love in the Time of Cholera, Vicky Cristina Barcelona)
http://www.imdb.com/name/nm0000849/