[harveywi]

The difference, in terms of type theory, is that a tuple is a product type [1] but a type representing multiple possible return values (to represent different outcomes) would be encoded using a sum type [2].

[1] https://en.wikipedia.org/wiki/Product_type

[2] https://en.wikipedia.org/wiki/Tagged_union

[eru]

I don't think eg Go uses a sum type:

https://gobyexample.com/multiple-return-values

Typically they use product types to simulate sum types.