In standard sizing (which the mfr. may or may not follow exactly) the measurements are:
Misses 14: 36/28/38 (back waist 16.5)
Women's 14W: 38/30/40 (back waist 15.5)
As a general rule, the W sizes (aka half-sizes) are cut more generously all the way around and are made for a shorter-waisted build. The bust is lower and the back is shorter than in a comparable Misses' sized garment. The neckline and armholes tend to be cut larger, too, but the sleeves tend to run a little longer, presumably to allow for a more fleshy shoulder and back.