Many. An ileostomy is made from the end of small bowel, tends to have a higher output and be more liquid and tends to be slightly more difficult to maintain. A colostomy is made from the colon (usually sigmoid) has output with a consistency of regular bowel movements. The are different situations (usually anatomical) for construction of one verses the other.
Location, location. Colostomy is surgically created from the colon opening to the skin. Sometimes temporary, sometimes permanent, depends on the cause for it. Usually on the left side, opens into a bag. Ileostomy is surgically created form the small bowel to the skin. Can open into a bag, or have internal valve ("continent ileostomy").