People -- men or women -- cover a wide variety of body shapes (mine goes pear-shaped if I don't keep an eye on my diet) but women are, basically, curvier than men.
It is NOT disrespectful to say so.
Many young girls get hooked on the skinny beanpoles featured in fashion magazines (it got so bad some years ago that they were promoting scarecrows under "heroin chic") and don't realise that full bodies are just fine. So they spending their time fretting and dieting, trying to create a body that looks like the air-brushed models in the fashion magazines.
Your mother is perfectly correct in saying that women are supposed to have curves. Be confident enough to enjoy your body, but try not to go over the top in either direction.
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The first two answers have come from men. You should pay attention to the women's answers when they come.