Diaphysis is a long bone ‘s middle part or shaft, consisting of cortical tissue. It typically includes bone marrow and fat. This is a compact bone composed of the middle tubular portion which surrounds a central marrow cavity containing red or yellow marrow. Primary ossification occurs in diaphysis.
Epiphysis is an extended end of long animal bones that ossifies separately from the bone shaft but is attached to the shaft at full growth. The epiphysis is composed of cancellous spongy tissue covered by a thin compact bone layer. It is connected to the bone shaft by the growth plate which helps to expand the length of the bone and is eventually replaced by the bone.
Diaphysis bone – The central shaft of any long bone.
Epiphysis bone – The rounded end of any long bone.