The answer is:
1. The term is shorter than for traditional mortgages.
3. A large payment is due at the end of the term.
in balloon payment mortgages, the buyers would had to pay considerably small amount before the mortgage is due. At the end of the term, the amount of mortgage is fully amortized and leave a huge sum for the final payment. (just like a balloon that start small and keep getting bigger as it pumped). This type of mortgage is very common in commercial properties.