The difference between Interrupts and Traps are simple. Interrupts are hardware interruptions as to where Traps are software – invoked interrupts.
Hardware interrupts are program controlled interruptions produced by some event external to the CPU. This stops the CPU from executing the code it was already running and to jump to the event that generated the interrupt. These type of interrupts can come from numerous sources, such as, expansion cards, timer chip, keyboards, and mouse, as well as peripheral devices. Most often, hardware interruptions do not ever occur because of event related program execution. When and interrupt occurs, the CPU is sent an interrupt request by the interrupt event, in order to provide service needed by the device and then returns to the normal program. Most often when a hardware interrupt occurs the CPU starts interrupt server routine (ISR) and other hardware interrupts are disabled.

The sole purpose of a Trap is to provide a fixed subroutine and can be identified as a transfer of control that is normally incorporated by the programmer. When a trap occurs, the CPU stops what is it doing like it does when an interrupt occurs, then it saves the context before jumping to the suitable trap routine. Then it completes and restores the context and continues execution.

Interrupts are a very important part of computer design. All computers have their own interrupt structure, which most of the functions are the same. An interrupt has to transfer control to the suitable ISR (interrupt service routine), in addition to being done in a timely matter. In a computer system only the established interrupts can occur, this allows the array of pointers, otherwise known as the “interrupted vector” used to store the address of interrupt routines. Traps and interrupts are associated with an index into that vector. The index values are a device number that provides the address of the ISR for interrupting device.