I think they are relatively similar.
The main biggest difference is the LightBoost motion blur reduction versus BENQ Blur Reduction.
They require different utilities for tweaking the strobe backlight.
XL2720T has LightBoost and works great with ToastyX Strobelight
XL2720Z has BENQ Blur Reduction works great with Blur Busters Strobe Utility
However, definitely make sure the XL2720Z uses a newer firmware (December 2013), because older firmwares in the Z-series are not adjustable via the Blur Busters Strobe Utility.