The plates are a world and away different, which makes the shoes, in turn, completely different. Saying they are the same based on the upper is like saying the Miler track spike is the same shoe as the new Rivals because they look the same (white with the red stripe). The plates are completly different to perform different functions, which makes them two distinct shoes.
Here is how the shoes are different:
The Lanang has the miler plate, which is an elevated forefoot and extends for only 3/4 of the shoe. This forces the runner onto their toes for more power and speed (like sprinting - since it was designed for mid distance races) and is obviously better for forefoot strikers.
The Vent plus, on the other hand, is non agressive and flat. The shoes was designed way before the development of the more agressive plates (ie miler, lanangs, and eldoret II) and the upper on the ST version was modified to make it a steeple shoe.