Are these stretchmarks or rashes - if stretchmarks will they fade over time?

These look like stretchmarks to me. Unfortunately, I have ugly tiger claw like stretchmarks too. Stretchmarks are permanent and can only be lightened. After I gave birth, my stretchmarks lightened considerably. Applying Vitamin E cream or Bio Oil liberally helps to moisturise the skin. It's not to say that it prevents stretchmarks, because that's genetic, but it will moisturise the skin and allow it to stretch a bit more.