Crawling is what babies do before they learn to walk. Anyone can crawl, using your knees and hands, crawling on "all four". Creeping along would be crawling in slow motion, hiding or sneaking up on someone. A cat can creep along and quietly wait until it has the right time to pounce on a mouse. Creep means to move slowly and carefully, in order to avoid being heard or noticed. "they were taught how to creep up on an enemy".

to CRAWL means to move slowly with your body on or close to the ground, or on your hands and knees, like my friend’s baby ;-) Their baby has just started to crawl ;-) to CREEP means to move very quietly and carefully so that nobody will notice you. For example my cat is doing it (The cat crept silently towards the bird).