A function generator produces standard periodic waveforms — sine, square, triangle, and ramp — at fixed shapes defined by the instrument. An arbitrary waveform generator (AWG) lets you define any custom waveform by uploading a point-by-point data file, making it possible to replicate real-world signals, simulate specific modulation schemes, or generate one-time transient pulses. AWGs are preferred whenever the signal shape is application-specific rather than standard.