You wouldn't really. It's the same concept as `τ = r × F`. the only difference is that it is useful to think of the 'type' of the output as being a bivector instead of a vector -- there's no sense in which it points 'out of the plane'; rather, it is a single vector in the vector space of (planes), with the same magnitude as r × F.

The distinct gets a little more useful when you start dealing with covariance under coordinate transformations. There it becomes more meaningful, because the _vector_ given by r x F doesn't transform the same way as their cross product should.

For an obvious example of why this is true: suppose r=x and F=y. Then r × F = z. If you change coordinates by mapping z -> 2z, then you would be doubling the torque that you computed .. which is wrong; the torque is unchanged. The bivector x^y is correctly unchanged by z -> 2z.

Currently in physics courses (usually not until more advanced mechanics or relativity) the resolution to this is to wave ones' hands and declare that, no, torque is a 'pseudovector'. But it is really much easier to think about if you type it as a bivector in the first place.