Game jersey sizing comparison

I want to order a jersey with the SB patch and amthinking to size down on what I usually buy. All my jerseys have always been L but a bit too big, (however with sixers jerseys I find L too big but M are way too small). I live in Prague so no chance to try anything on….

How much difference is there between the two? Does anyone have one of each size they can take a photo for me with the M on top of the L? Thanks :)