Frist I want to point out that the smooth muscle pertains to organs and skeletal muscle pertains to the bones.
The difference between the function of these two types is that: (think about it for a second, what do organs do?) Organs allow for things to pass through or be processed or created when they are contracting. For example: your bladder contracts to release urine.
(Think about bones and why we need muscle attached to them, If we only had bones and nothing attached, we wouldn't be able to move. We would just be a sac of bone and organs.) Skeletal muscle contractions allow us to move. For example: when you move your arm the muscle contracts allowing that bone to move in the position you are moving it.
-Medical Student (College Level)