The 2836 is .5mm thicker than the 2824 because of the different calendar works (otherwise its essentially the same movement) - it will give an incorrect crown height, which bothers a lot of people around here, even if they can't see it. (its 0.5mm). The 2824 is also significantly cheaper.
Are you sure about the prices?
At Puretime the 2836 is from VRF and the 2824 is from ARF. The ARF cost more than the VRF, so the 2836 is cheaper than the 2824...
0,5mm crown height difference is hard to notice but in conjunction with the shape of the CGs you will notice it. The result is a totally wrong CG shape.
This is a good reason to buy the 2824...