Q. Is there a difference between sins? Is telling a white lie the same as murder and /or rape, and so on?

Yes, there is a great difference. The latter two are enormities (kaba'ir). Telling a small lie is far less offensive. If you lie in order to reconcile a husband with his wife, for example, it is actually praiseworthy. E.g. in telling each that he/she spoke well of the other when that is not necessarily the case, in order to move their hearts towards reconciliation. And Allah knows best.