Final answer:
The diaphysis is another name for the shaft or longest part of a long bone, while the epiphysis refers to the wider ends. The diaphysis is filled with compact bone and contains a medullary cavity, while the epiphyses are filled with spongy bone and red marrow.
Step-by-step explanation:
The diaphysis is another name for the shaft or longest part of a long bone. It is the tubular portion that runs between the proximal and distal ends of the bone. The diaphysis is filled with compact bone and contains a hollow space called the medullary cavity, which is filled with yellow marrow. On each end of the diaphysis, there is an epiphysis, which is wider and filled with spongy bone and red marrow.