If i dont have my fancy words in the wrong order there's basically 2 ways of looking at modes. parallel and relative. Where relative basically takes the scale and gets you to start on another scale degree to create a mode. And where parallel just alters the formula of the major scale; my way. Personally i have always learned it in the last way, just like how i learned every scale. You take the major scale, apply the proper formula and there you go. So that got me thinking, why does the other approach exist? Whats the pro's and con's and where does the first approach actually come in handy?