The terminology changes between processors and operating systems, this is one interpretation:

1. an interrupt is a signal from a hardware device to a processor that some even has occured, this allows the processor to service the device, an example may be a serial port that generates an interrupt every time a character is received or it's transmit buffer is empty.

2. a trap is a mechanism to get from user space to system space, typically used in a protected operating system to transfer control from a user program to the kernel.