Because of different paint apps, or plastic colors, some even have unique coo markings.
First I would suggest reading the guide. Pretty much all the answers you will ever have about ledy will be in here. For instance the han you posted pics of you can clearly see the difference to the paint apps on the head. The ledy paint mask made hair come down over the sides of the ears where as the Kenner did not. Combined with the darker brown plastic of the pants. All ledy figures have unique traits specific to them.
I have caviar dreams and McDonald's pockets