Hi technically there is no difference between a ported or vented box. However, what the guys here are mincing words about is that in the last 5 years or so people have started using a "vent" type of slot for a port in sub boxes. The advantage to this was to reduce the wind noise that ports can make at high volumes if the subwoofer is moving a lot of air. Slot style vents are able to let the air move out more freely and not produce a "chuffing" sound. So that's what the guys here are talking about, and why you see most nicely done ported boxes use flared ports so that the airs moves out with less turbulence. If installed properly slot type vents work nicely and have inherent disadvantage to tradition ported boxes. They are more time consuming to build and can't be "fixed" easily by simply shorting the port like the regular cylindrical ports can. Hope that helps.
Anthropas