and what is the diffrence between it and the other engines?

Opus is right, Quattro is not an engine, it's Audi's full-time, all the time all-wheel drive system.

Check these quotes from www.audiusa.com/quattro

"quattro®
Audi's quattro® permanent all-wheel drive, now in its fourth generation, has a 20-year-long tradition. The idea was simple enough: Transfer power from front to back and side to side as needed. After all, a wheel spinning is wasted motion. Along with better performance, quattro provides high levels of active safety and improved traction on virtually all surfaces. On cars with longitudinally installed engines, a Torsen® differential distributes power and compensates for differences in wheel rotation when cornering; if the car has a transverse engine, these tasks are performed by a Haldex® clutch"

And/or...

"In 1980, Audi introduced the world to something new. Full-time all-wheel drive to volume-produced passenger cars. We called it quattro. We still do. Now in its fourth generation, Audi's quattro® permanent all-wheel drive directs power where and when it's needed.

Under ideal conditions power is split 50/50 front to rear. But in extreme cases up to 67% of the engine's power can be directed to a single wheel. The benefits to the driver are safety, performance, power, and control in copious amounts.

While no drivetrain can repeal the laws of physics, quattro affords drivers the chance to act, not merely react. In fact, it's that added measure of confidence that Audi drivers cite when asked why they chose our brand of all-wheel drive."

There's even an illustration for that...

Opus you need to go back to school.
"Quattro" Four Valves Per Cylinder. By doubling the number of intake valves supplying each cylinder and the outlet valves channeling the flow of exhaust, engine power is substantially increased. Twin overhead camshafts drive the intake and exhaust valves promoting free-breathing efficiency and free-reving performance, while precise valve timing is syncronized with sequential fuel injection to supply each cylinder with the correct volume of fuel-virtues derived from the engine's racing predecessors. The result: a consistently responsive flow of power.

Just a little info. Hope it helps!