I’ll understand if this hasn’t been a burning question for you. But I’ve always struggled to identify correctly when one is put in front of me. Turns out, after sleuthing, they do have separating characteristics along, colour, the tightness of skin and the amount of seeds. I had to go 3D, but I think this should allow you to identify the next small orangey thing that you eat.
For the record:
Mandarin Has seeds, loose skin and is orange
Clementine Seedless, tight skin and orangey-red in colour
Satsuma Seedless, loose skin and orange
Tangerine Has seeds, loose skin and is orangey-red
PS I promise no more mandarin-related sketchplanations in a hurry