What is a medical onconologist vs. a clinical oncologist?

Same: "clinical" usually means a doctor who works in the clinical setting, ie seeing patients. A medical oncologist is a doctor who treats cancer patients with medications and chemotherapy. A "clinical" oncologist probably means the same thing, although it's not a term i've heard used very much.

Clinical Oncologist: Is used in South Africa and israel, where it is common for people to be trained and use both chemotherapy and raditherapy. It is also used in great brittain where medical oncology is not a "recognized" specialty, but there are many leaders who we would call medical oncologsts if they were here. It's an exotic term here; we do not use it.