ease = starts slow , speeds in middle and slow again in the end.
ease-in = slow in the beginning , speeds up in the end.
ease-out = speeds in the beginning, slow in the end.
linear = as the name suggest, i.e. constant speed throughout the animation.
ease-in-out = starts slow, fastest in the middle , slow again in the end.
DIFFERENCE BETWEEN EASE & EASE-IN-OUT