Whats the difference between the natural minor and melodic minor scales? And how do you diminish a scale????

natural minor is 1-2-b3-4-5-b6-b7 ex. in C: C,D,Eb,F,G,Ab,Bb
melodic minor is 1-2-b3-4-5-6-7 ex. in C: C,D,Eb,F,G,A,B
difference would be natural minor has a flattened 6th and 7th interval.
and diminished is 1-2-b3-4-b5-6-7 ex in C: C,D,Eb,F,Gb,Ab,A,B

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No, melodic minor is something else. It changes going up and coming down. It goes like:
Scaleing up: 1-2-b3-4-5-b6-b7-8
and going back down : 8-7-6-5-4-b3-2-1
So the guy before me has it right for going down the scale, but going up it it's just natural minor, it's a really weird scale, I never use it.