The one I like is the ILS 16L at SEA. The category A minimums are 60 feet higher than the B, C and D minimums. When the TERPS people did all the sums they figured a slow aircraft with a strong crosswind could be blown too close to the control tower so they set the category A mins at the height of the control tower. A faster aircraft would not be displaced as much by the crosswind and so can go lower.
Flying Hog, without knowing which airport it would be hard to say why the minimums are different.