Conventional, SBA, Correspondence, and Private.
Conventional Financing is funding through a traditional bank for an Investment Property which typically requires a minimum down payment of 30%.
SBA Financing is funding through the Small Business Administration for an Owner-User Purchase which requires the Buyer to be an established business who plans to occupy of the property. The beauty of this type of loan is it only requires a 10% down payment and is for 25 years!
Correspondence Financing are much larger Commercial Loans and underwritten by either an Insurance Company or Wall Street firm. These loans are highly restrictive and include large Prepayment Penalties.
Private Financing is funding through typically wealthy individuals or small Mortgage Companies, and typically involve above market interest rates and higher loan origination fees or points. The advantage of this type of loan is minimal personal documentation is required, but a Borrower pays dearly for this.