They are in fact the same concept: Any is an existential with no constraints. (Once upon a time, protocol composition was spelled protocol<P1, P2> instead of P1 & P2, and Any was a typealias for protocol<>.)
I do think it would be easier to understand this if we change the spelling of Any to any somethingOrOther, but I don’t have a clear proposal for what somethingOrOther should be – Value has been suggested, but that’s confusing given that we often talk about “value semantics” applying to a subset of language values.