Differences
Sea Stars have five or more arms while humans have one.
Sea Stars have spikes on their outer covering.
They do not have a circulatory system because they do not have a heart or blood that circulates nutrients.
Sea Stars have two stomachs while humans only have one.
They move very slowly and with the aid of tube feet and their water vascular system that humans do not have.
They are invertebrates while humans are vertebrates.
They can see much less than humans and do not have a brain in their nervous system.