The Departed was based on the Hong Kong film Infernal Affairs. It has a prequel as well as a sequel too. I don't understand Chinese and had to rely on subs.

But, I had watched Infernal Affairs before Departed came. Martin Scorcese was awesome, Walhberg and Damon are my favs, but still, I liked the original more than the Hollywood adaptation.

I think you watched Departed first and then the original, which would have caused the original to look inferior with the Hollywood one.