From what I can tell, Ensure is pretty much the same thing. I certainly don't consider Soylent to be a revolution, beyond perhaps a marketing revolution in the tech community.

Ensure does provide an option, but it's relatively expensive, lacking the full range of nutrients found in Soylent, and pretty high in sugar (though I think they have just reduced sugar slightly).

Ensure is cheaper, but it's not a full-fledged meal replacement product. It's intended to be a supplemental product to an otherwise normal diet.

"Ensure" is a whole line of different products with different roles. Ensure Complete seems to be at least as much of a meal replacement as Soylent.

I fed my brother Ensure through a tube in his nose for 2 months before an intestinal surgery. The doctors considered it as good of a meal replacement as any for that amount of time.