Mic In and Line In are both types of audio input ports on a device. The main difference between them is their level of sensitivity. Mic In is designed to receive audio signals from a microphone, which are typically very weak. Line In, on the other hand, is designed to receive audio signals from line-level sources, such as audio mixers or musical instruments, which generally have a stronger signal. So, the difference lies in the type of audio signals they can handle.