Infernal Affairs vs The Departed - The Introductions

He we go with the first set of movies. For your edification I will include a link to IMDB, but I'll also write a few lines about what I know going in. Also, I'll include a trailer for you.
Infernal Affairs (2002) - A Story about two motivated young men working on opposite sides of the law, but they come from the same past. Considered to be one of the best products of Hong Kong cinema in recent times, this is a modern classic in it's homeland.

http://www.imdb.com/title/tt0338564/

The Departed (2006) - Filled with an all-star cast and directed by an American directing legend, "The Departed" won an oscar for Scorsese in 2006. An American retelling of the 2002 film "Infernal Affairs", this time set in Boston Massachusetts.

http://www.imdb.com/title/tt0407887/