Some of them are backed by the government. VA loans are for individuals that have been or are in the Military. FHA loans are very good for a low down payment and competitive rates. FHA loans are also more lenient on credit challenges. The VA and FHA loans do have requirements for the condition of the house.
Conventional loans are great products too.
Conventional loans do not have nearly as many requirements of the property. A fixed rate is just that. The interest rate will never change. It will stay the same for the life of the loan. An ARM normally has a lower initial interest rate for the first few years.