Compare two surveillance videos for two days and find different

I want to compare two vedios for the same camera and find different, this two vedios are surveillance video for two days. give me some idea,thank you.

welcome. please explain the approaches you have tried.

Just make a frame by frame substraction , if more than 10% of the pixel are different for 10 consecutive frame, there is a difference.
This method is very sensible to noise but it s a start