Traditional singing lessons will take you through all the runs in all scales in your natural speaking voice and help you accomplish steady notes.

Metal singing lessons are specifically designed to help you develop a new skill, a new rasp, the ability to scream effortlessly. This skill is very hard to develop without guidance and can get a bit complicated. You don’t want to hurt your voice, there are ways to incorporate a rasp into your style of singing but going at it the wrong way can hurt your throat. You have to start with baby steps. Not everyone knows how to access different parts of their voice and not everyone knows how to teach the way to access these skills. That is why it is important to ask your vocal coach what you can expect to learn in their class. 

If you express the interest in learning metal, and your vocal coach is not too sure about it, look for a different coach. Look for someone that is confident and knowledgeable in the genre. It is not something you should gamble with. Getting the right vocal coach from day one can save you so much time, effort and money.