Astrocytoma or ependymoma?

My husband was diagnosis (from histology report) with astrocytoma II of the spinal canal in 1972. In 1978 a tumor was found in the 4th ventricle of his brain. It was classed as inoperable. At the time both tumors were treated with both radiation and chemo. Today he has multiple tumors  virtually running the whole length of his spinal cord with a large associated syrinx. However looking at all the reports we have gathered over the years there seems to be confusion as to whether he has astrocytoma or ependymoma or both. What is the major differences between the two and can they be told apart by their appearances on MRI. Any help would be greatly appreciated.

Kind regards
Sharon