Days - Anyone else have trouble telling Kayla and Adrienne apart?

I saw Adreinne on the show today, and I thought it was Kayla at first until she mentioned Stephanie being mad that "I told Kayla about the pregnancy issue." When I saw her, I though, "What is she doing back already" because she's off in Africa or Switzerland or wherever. How can I tell these two apart? I wish one would die their hair or something. That would make it a lot easier. Also, are Kayla and Adrienne sisters or sisters-in-laa?