Specifically,

If v_i = 0, then
a = v_f^2 / 2s [ s = distance travelled]

And from newton's 2nd law, a = F_net / m [ m = mass of object]

But I've tried to them on a bunch of different problems, and they're never equal.

Are these two different accelerations? Or how can I relate them properly?

Specifically,

If v_i = 0, then
a = v_f^2 / 2s [ s = distance travelled]

And from newton's 2nd law, a = F_net / m [ m = mass of object]

But I've tried to them on a bunch of different problems, and they're never equal.

Are these two different accelerations? Or how can I relate them properly?

Example:

A Particle with a particular mass being acted on by different forces from different directions travels a particular distance and achieves a particular velocity. Different accelerations are found by using the two methods. Which one is correct?