Jargon: Sum Type, Discriminated Union, Tagged Union, Disjoint Union (2016)
The jargons {sum type, tagged union, discriminated union, disjoint union} have same meaning but with nuances in different context. (e.g. in math, and in different programing languages.)
Sum Type
Discriminated Union
Discriminated Union in Fsharp
Tagged Union
Disjoint Union