Algebraic geometers use both terms for the same thing. From [1]: > In algebraic geometry, a torsor or a principal bundle is an analog of a principal bundle in

Algebraic geometers use both terms for the same thing. From [1]: > In algebraic geometry, a torsor or a principal bundle is an analog of a principal bundle in algebraic topology. So I wouldn't be too surprised if other people confuse this too. [1] https://en.wikipedia.org/wiki/Torsor_(algebraic_geometry) https://en.wikipedia.org/wiki/Torsor_(algebraic_geometry)