Canvas Images are smaller than Game Objects

An image inserted to a canvas is smaller and not accurate in terms of pixels per unit compared to a Game Object with a sprite renderer using the same source image (which is accurate in PPU). Why is this happening?

 

Orthographic size of the camera also plays a part in the size of the sprite being rendered. With a canvas scaler set to the current resolution as reference the UI images should be the correct size, then you adjust the orthographic size so it matches.

 

Also check the pixels per inch setting on each sprite itself