Mortgage-backed security (MBS) is comparable to asset-based security (ABS) (MBS). Both are fixed-income instruments that, like bonds, pay a fixed rate of interest on a pool of income-generating assets, generally debts or loans. The key distinction is that an MBS, as the name indicates, is made out of a collection of mortgages (real estate loans). An ABS, on the other hand, is typically backed by other types of debt, such as college loans, vehicle loans, or credit card debt.
Some financial sources use the word ABS to refer to any type of securitized investment based on underlying asset pools, in which case an MBS is a type of ABS. Others regard ABSs and MBSs as two distinct investment vehicles.