Page "Operational amplifier" Paragraph 4

The op-amp is one type of differential amplifier.

Other types of differential amplifier include the fully differential amplifier ( similar to the op-amp, but with two outputs ), the instrumentation amplifier ( usually built from three op-amps ), the isolation amplifier ( similar to the instrumentation amplifier, but with tolerance to common-mode voltages that would destroy an ordinary op-amp ), and negative feedback amplifier ( usually built from one or more op-amps and a resistive feedback network ).