There are striking differences in the macronutrient ratios and in the prices. Soylent (Huel, etc) are much closer to the USDA recommended macro ratios, and have much less sugar. Only Ensure Original is less expensive than Soylent, all the other Ensure products (there are several) are much more expensive per calorie.
[0] http://futurefood.hellobox.co/soylent-is-not-ensure-and-why/...