I tend to agree, but if there's any difference, for me it's that a white lie might be bigger in scope, but always with good intentions:
You look absolutely beautiful in that dress. (I love you, so I want you to feel beautiful, but that is really the most hideous thing I've ever seen.)
A fib is trivial, but the intention of the liar is not necessarily good:
No, I didn't eat the last cookie. (I don't care that it was for my brother, I wanted it, and I don't want to get in trouble.)
I'd say it's more a difference of tone. "Fib" is more familiar and often used to children. The implication is that a fib is harmless and on the small side. Whereas a "white lie", as others have said, is standard English for a lie told to spare someone's feelings.
No I think it's more than 'tone': a white lie is 'a lie that is told in order to be polite or to stop someone from being upset by the truth' (Cambridge Dictionaries). A 'fib' is 'a trivial or childish lie' (Merriam Webster). As Kelly indicates, their intentions are likely to be quite different.