Ummm... tips? I don't really know since I recognize them easily and I don't really think they look alike. XD Let's see...
CURRENT HAIR:
Sun Mi ---> Dark long with really thick bangs
Eun Ye ---> Long red-ish without bangs
LOOK:
Sun Mi ---> Cute
Eun Ye ---> Sexy, mature
EYES:
Sun Mi ---> Big & round eyes
Eun Ye ---> Small & slanting eyes (that's how I recognized her at first)
Here's a picture where you can clearly see the difference with their eyes.
First girl: Eun Ye ... Fifth girl:Sun Mi