Uh oh, I sense a little confusion here...

FIV - Feline Immunodeficiency Virus - also called "cat AIDS" because it is the feline version of the Human Immunodefiency Virus and as such the symptoms, outcomes, and modes of transmission are very similar.

FeLV - Feline Leukemia Virus - another disease that is caused by a virus and also manifests itself by causing a suppressed immune system, but is not the same as the FIV virus and although can have some of the same symptoms as FIV, and can have a different outcome than FIV, is usually transmitted in other ways than FIV.

Many cats with FIV will live many years beyond original diagnosis. Many cats with FeLV live only a few months after original diagnosis. Many cats with FIV will exhibit no symptoms at all, or will have opportunistic infections showing varying symptoms. Most cats with FeLV will have upper respiratory symptoms. FIV is not highly contagious as the mode of transmission is believed to be only through bodily fluids. FeLV is very contagious as the mode of transmission can be through saliva as well as nasal, eye, urinary and fecal secretions. Also, like HIV, the FIV virus is not believed to live long outside its host because it is easily killed in dry, cool environments. But the FeLV virus can survive outside its host for an undetrmined time.

It has not been determined (at least last I heard) if the human leukemia virus causes cancer of the blood, although it has been suspected for a long time in some types of leukemias. HLV causes such diseases as mononucleosis and Eppstein-Barre. It has been suspected in Chronic Fatigue Syndrome, since its symptoms can be similar to mono and EBV. So in that sense FeLV is much like HLV. If your cat has an FeLV infection, he does not have cancer, he has an infectious disease.

So, FIV = HIV
and
FeLV = HLV but is not cancer

I hope this clears up some of the confusion.