Programmable logic array (PLA) and programmable array logic (PAL) are generally known as programmable logic devices (PLDs) that have programmable AND array, but with a difference in which one has an additional fixed OR array while the other has an additional programmable OR array.
But what is a programmable logic device?
Programmable logic device (PLD) can be thought of as a blank slate device that can be programmed or reprogrammed depending on the type to perform a logical operation or function.
Programmable here does not denote programming in C or Python, but it is a way of controlling logic circuits so that logical operations can be performed.
PAL is said to be a PLD with a programmable AND array and a fixed OR array.
You can easily recall this from the fact that A is between P-A-L which means the AND is programmable but the L outside designate that it has a fixed OR array. If you can recall this, then PLA will be easier.
PLA is said to be a PLD with a programmable AND array and a programmable OR array.