Here is a nice overhead shot illustrating the difference between the Plaza last and the Grant last. Grant in #8 on the left, Plaza in black on the right. Both of these boots are made using the same pattern.
Both have a sleek and tapered toe box but the Plaza is more angular and chiseled. I have not tried either last myself so I can’t comment on the fit, but I sure do like the Plaza for its looks. Very handsome.