What is portrait mode in camera?

I think it works by focusing the subject while blurring the background (from Canon). But when I've tried portrait mode on my nikon, the background is not blurred. Why? Is there different functions of portrait mode in every other camera?

The functions are the same (large aperture, lower ISO), but the effect also depends on the focal length and the distance from subject to background in relation to the camera.

A blurry background depends on three things: aperture, focal length, and distance. Portrait mode will only set the aperture. Zoom (focal length) and distance is up to you. I think if you compare the two cameras with the same zoom and distance, you will get the same blurry background.