What is the main difference between a balloon mortgage and ARM?

A balloon mortgage features a fixed interest rate for a set period, after which the remaining balance is due in a lump sum payment, often leading to the need for refinancing. In contrast, an Adjustable-Rate Mortgage (ARM) has an interest rate that can change periodically based on market conditions, typically starting with a lower fixed rate for a few years before adjusting. While both can offer lower initial payments, the balloon mortgage carries more risk at the end of its term, whereas ARMs can fluctuate in monthly payments throughout the life of the loan.