Generally they are going to be more full featured. More ports, better NICs, better on board sound, chips to multiply PCI-E lanes, etc.
If you are a color purist and want a gloss screen, pick up a Samsung S23A700/750D. Fry's has been running sales for in-store purchases on them for the last few months. Quite a few of them still carry them. The ASUS VG236H is really hard to find, and offers similar color quality with a lower input lag than the Samsung. If you can score a used one, I'd have no reservations about it.
The new ASUS 144Hz screen is supposed the to be out soon too.
LD PC-V7 will be in stock at Frozen CPU by the end of this month, hopefully. Much much better case than the 900D.