What are the differences between a trap and an interrupt? What is the use of each function?

An interrupt is a hardware-generated event, usually caused by an I/O
device requesting service.  A trap, on the other and, is a software-generated interrupt.
Traps are caused by 1) system calls and 2) exceptional software
conditions (e.g. Divide by 0). Other than the source and function,
processing of traps and interrupts is the same.