It has to do with the end of the end cap. I haven't tried the moto personally but they've got a outer-bump at the outside (the flat do not have this outer-bump). The Tapered ones are nice they have a gradient and flare bigger towards the outside of the end cap so your hands have a little extra room on the edge of the grips and it won't get pinched by the end of the ODI clamp.
I often rode with my hands on the absolute end of the ODI end clamp and would sorta pinch the end of my hand as the end cap just drops off. The tapered ones don't do that now and they made my hands feel a lot more natural as there's a better size increase (gradient) towards the end cap that flares a little bigger. Hope that's not too confusing. Give them a call if you want to know more, they'll tell you about it more.