Distinguish between theoretical mechanical advantage. How would these compare if a machine were 100percent efficient?

Theoretical mechanical advantage of a system if the ratio of the force that performs the useful work to the force applied, assuming there is no friction in the system. Actual mechanical mechanical advantage takes into account energy loss due to deflection, friction and wear. If a machine were 100 percent efficient, the actual mechanical advantage would be equal to the theoretical mechanical advantage, as no energy would be lost to the surroundings.