Both antennas perform very similarly and have the same wind speed rating.
Overall the slow taper antenna has a greater surface area. It is "stiffer" and bends less in the wind. It also has a wider "bandwidth." Which, for a non-resonant 43 ft. antenna, means that once it is tuned for a given frequency, you can move further up or down the frequency before needing to touch up the tuning using your transmatch.
The fast taper antenna has a smaller surface area.It is a little more flexible which will cause the antenna to curve more in the wind. However, the process of curving in the wind allows the antenna to "shed" some of the wind load.