What is the difference between the LectroSound and LectroFan models?

The LectroSound is a white noise generator. It uses custom analog circuitry to create a white noise sound field that’s warm, robust, and truly random. You can use the tone  dial to precisely control the output by adding noise from the brown and pink ends of the spectrum.
LectroFan and LectroFan EVO provide ten fan sounds and ten variations of white noise, ranging from brown, to neutral white, to pink. The EVO also offers two ocean and surf sounds.