Jaw Titan Vs Ymir / In ymir's case her titan form was noticebly similar to her mindless form because the titan gets the look from the shifter, you can notice that ymir herself is an interesting case, she'd probably be classed as an abnormal.

Ymir and the jaws titan explained!in this video we look at all the evidence from the attack on titan manga, anime, and extra material to explain the secret.