The main reasons we classify muscle types is because they vary in their structure, function and location. Whenever, trying to remember the differences start with the easiest first. Then compare and contrast the different muscles and try to think of why they are designed in that way. Most basic textbooks cover the details of skeletal muscle contraction so I will focus more on comparison rather than reiterating a lot of the information you are likely familiar with already.
As obvious as this appears skeletal muscle is attached to the skeleton, cardiac muscle makes up the heart and smooth muscle is everywhere else like the gastrointestinal system, arteries, etc.
Structure & Function
Skeletal - This muscle type is attached to the bones of the skeleton with tendons made of collagen and through their contraction/relaxation they maintain our posture and allow movement. Skeletal muscle is the only muscle under conscious control, which means if I want to lift my leg I will be able to control the muscles in my body to do so. The muscles are innervated by motor units which are essentially nerves that innervate the muscle. Skeletal muscle cells are multi-nucleate which means they contain more than one nucleus. The nuclei are flattened and located near the sarcolemma. The muscle cells form fibers that look like long skinny cylinders. These fibers have light and dark bands called striations that result from the arrangement of contractile units.
Cardiac - ...