Toprope means the ropes are already hanging through the anchor above. On 1 end the climber is climbing stress-free and on the other end the belayer is belaying (keeping the rope tight). There is no fall factor.
Lead climbing means there are no ropes hanging through the anchor above. While climbing, the climber clips quickdraws into the bolts and threads the rope through the quickdraw, exposing the climber to a fall-factor. This is not stress-free.