I dunno. They have no idea if EN works why it works.
there's many theories:
-it's a nutritional therapy, it restores deficiencies which decreases gut permeability
-it modulates the inflammatory response
-it modulates the intestinal flora
-it's because it uses medium chain triglycerides
-it's because it is extremely low in microparticles
they don't really know
As far as Boost and Ensure. Boost and Ensure (and Fortimel / Fortisip etc) are very very different from 028, Modulen etc.
They don't have the same type of bioavailable whey proteins like hydrolised whey, they don't use the same type of dried glucose that EN tend to use, they use other types of fats than medium chain triglycerides. I don't know what is all in Boost and Ensure, but it's not comparable to "real" EN. They're really low quality products in my opinion. That's also why they're considerably cheaper, if EN is cheap it's probably not any good, isolating whey without denaturing is an expensive process, it can't be done on the cheap.