My car is overheating while moving and is leaking coolant into the oil. What's wrong with it?

I would be thing more along the lines of a head gasket problem, you can get a head check done, this is a quick and simple chemical test to check for exhaust gasses in the cooling system, I would start here.

They are just using different names for the same diagnosis. This may or may not be the actual problem and it may be difficult to pinpoint the specific problem without disassembly. It could just as easily be a bad intake manifold gasket or blow head gasket. It needs to be diagnosed properly.