There is a ladder of capabilities and categories for field programmable logic devices, and an array of acronyms to match! In truth, the boundaries between EPLD, FPGA, and SoC(System on a Chip) are as much a function of manufacturers’ marketing departments as of device architecture. There are various ways of holding the configuration data for the device

A major consideration in device selection is operating voltage. Older device families were designed when 5V operating was the norm, and whilst newer device families are orders of magnitude cheaper per logic gate count, the associated savings in FPGA cost have to be offset against the cost and complexity increases due to logic level translation.