Like I said the HZ27WB is Wide gamut which means its's got better colour coverage, but no game supports it afaik. Some but not all image editors do support it.
The colours of the HZ27WC will have more of a punch to them as it's a glossy monitor while the HZ27WB is a matte monitor.. tbh, the HZ27WB isn't very attractive because the Dell u2711 isn't much more expensive but Dell has a perfect pixel policy and a ton more connection possibilities. What makes the HZ27WC (and WD) attractive is that they're the only glossy IPS monitors (not entirely true, the Apple cinema displays are glossy too but twice the price).