what is the difference between analog and digital resolver?

Answer 1

An analog resolver can only resolve analog signals. The quality of analog sigals is not high.

Similarly, a digital resolver can resolve digital signals. Digital signals lead to high quality.

Signals can be audio or video.

Answer 2

I believe you're asking about servo equipment...

Analog uses a variable resistor (potentiometer) and the servo uses the voltage (or current) output from the potentiometer that varies directly with regards to position for feedback.

Digital uses an encoder (usually an optical encoder) that provides a digital code output that varies directly with regards to position for feedback.