What is the difference between a red dot/reflex scope and a holographic scope(NO C.O.D.!!! REAL LIFE ONLY)?

Please no call of duty. I don't care about how the game play is affected by either of the scopes. I have a SCAR that i spent $4500 to get it shipped here. Before i put a tactical sight on it (ACOG model TA-01, Aimpoint compML3 red dot, or an EOTech 552A651 holographic sight) i would like to know the difference between a holo. sight and a red dot. If terrain makes any deciding factor, i live 50 miles south of Wichita Falls, TX. I'm looking for durrability, longevity and something easy to shoot "on the fly". Thank you.