HUMAN SKELETON -
Hard supportive or protective elements of the animal body form the skeleton system. It's study in osteology.
EXOSKELETON -
Present outside skin. It consists of nails, hair etc. Keratine protein present.
Covers the body. Produced by ectoderm. Consists of non-living material. May be moulted periodically during growth.
ENDO SKELETON -
Occurs inside body. Produced by mesoderm. Consists of skeletal tissue as bones & cartilage.