Ensure Complete describes itself as "Provides balanced amounts of macronutrients and essential vitamins and minerals." Lacks the micronutrients needed. Strikes me as intended for "we really don't have any other options at this point" and consequential symptoms will be treated as illness.

Nutrament describes itself as "This nutritional drink is ideal as a snack, an occasional meal replacement, or a perfect post-workout drink." Note the "occasional"; it's filler augmenting an otherwise sensible natural diet.

Soylent is intended as "you can live on this stuff full time", which its creator does. He's suffered some pretty painful & weird symptoms of not getting everything right (like inadequate micronutrient supply causing bizarre cravings), and felt profoundly satiated when he did get it right.

Anecdote: I once worked on a portable IV pump intended to "feed" people lacking most of their GI tract, injecting nutritionally complete "meals" directly into the bloodstream. Each "meal" cost about $300.

Not that different, other than the recipe being public and the ability to make it yourself. The purpose is mostly the same, though Soylent aims to be sustainable, while most of these meal-replacement concoctions warn against prolonged usage. That might just be playing it safe though.