Point-slope form y - y1 = m(x - x1) is used when one point and slope are known. Two-point form eliminates the need to calculate slope separately: $\frac{y - y1}{(y2 - y1)}$ = $\frac{x - x1}{(x2 - x1)}$. In JEE, point-slope form is preferred when the slope condition comes from parallelism or perpendicularity to another line.