GSEs include the Federal Home Loan Banks (FHLB) and the Federal Farm Credit Banks (FFCB), which are systems comprising regional banks. The Federal National Mortgage Association (FNMA or Fannie Mae) and the Federal Home Mortgage Corporation (FHLMC or Freddie Mac) are privately owned corporations created by the federal government to provide liquidity and increase available credit in mortgage markets.
Federal agencies like the Government National Mortgage Association (GNMA or Ginnie Mae) are backed by the full faith and credit of the U.S. government. GNMAs are commonly issued as mortgage pass-through securities.