How do you change out the a/c compressor in a 1995 Jeep Cherokee?

I removed the old a/c compressor from my 1995 Jeep Cherokee Sport. However, the fittings on the back of the new compressor do not match the hose fittings on the car. The fittings on the new compressor are much smaller than the ones on the compressor that came off of the vehicle. In fact, the new ones are two different sizes while the old ones appear to be the same. Everything else abouth the part looks the same. I have confirmed with the parts place that I have the correct part. How do I get the new part to connect to the old fittings on the car?