Guitar players-is death metal really hard to play?

It depends there are bands like Necrophagist who are very technical and fast, then theres the bands that just switch between power chords and have no solos or any technicalities such as mortician.

its much easier because high distortion and playing fast sounds out the mistakes (you cant hear them) but if your playing just rock/clean say u hit another string or the wrong note and everyone notices but not with death metal

That depends. Generally, yes it is. Most death metal, hardcore, and thrash metal require an extensive knowledge of the scales. Usually a great technical knowledge is required. Practice makes perfect, love. Keep at it, and you'll get it. I've seen a lot of people go from average guitar players to being stars on the local scene in metal ^-^

Cheers