The finer portion of the Vortex BDC reticle is .2 MOA, and the Nikons are .24 MOA as advertised at the optics highest power.
The subtensions of the Vortex dots are 1.5, 4.5, 7.5, and 11.0 MOA at optics highest power. The reticle is technically not a MOA reticle since the dot subtensions don't repeat, like say the Nightforce NP-R reticles. The subtensions are designed to match some arbitrary trajectory [as all BDC reticles are designed to do], which may or may not fit another trajectory in even hundred yd. intervals. All BDC reticles will fit some trajectory depending on conditions, but none will fit all trajectories.
When a BDC reticle doesn't fit a particular trajectory it has to then be applied for such just like one would apply a mil-dot or MOA reticle, easy enough to calculate and test the same as any other multi-stadia reticle.
Personally i like the windage points of either reticle very well, or at least as well as any BDC reticle that's not a tree reticle system--my preferred BDC reticle for field apps.