Question

What’s the difference between m=change in y and change in x and m =y2-y1and x2-x1

Answer 1

it's the same thing

$slope = \frac{Δy}{Δx} or \frac{change \: in \: y}{change \: in \: x} = \frac{y2 - y1}{x2 - x1} = \frac{rise}{run}$