Short sale of MGC difficult?

Hi, folks. I am working a short sale on a MGC Mortgage loan, a 1st lien position where the mortgagor is an owner-occupant living in the house, not an investor. Is MGC hard to discount? Also, when I asked if the loan was FHA, Fannie Mae, or conventional, they said it was a private loan. Is there a difference between a conventional and a private mortgage loan? If so, is it harder to discount a private mortgage loan? TIA.