What's the difference between sounds and vowels

It depends, but a sound is like a normal letter, for instance, L is a sound and a vowel is A E I O U and sometimes Y. so, the difference is the structure the letters are pronounced. vowels, are shaped more with the mouse, so a word without a vowel is just, for instance, "Namjoon" would be "Nmjn"

Well a vowel is a speech sound made with your mouth fairly open, the nucleus of a spoken syllable. A sound made with your mouth fairly closed.