Question about calculating the difference in volume of spheres

If I have two spheres of known volume and want to calculate the differences in volume, is it valid to subtract the smaller volume from the larger, or am I violating some obscure rule of geometry?

Thanks

Yes, this is valid since we usually seek a difference in volume that is a positive number.
The larger volume subtracted by the smaller volume.

We could go the other way in which case the difference would be negative indicating that the volume has decreased from the larger to the smaller.