just a suggestion
Matchback for this.
The greatest difference in the world - the abstract, immaterial, virtual-sectored world - is that between the number one, and all other numbers.
(Special consideration and honorable mention might also be made for the eternal distance between one, and zero.)
A machine can much, much more easily be built for one user than it can be for two. The interfaces are simpler, opaquer to error.
The ability of two different users to access the same interface with the same level of facility does not imply that those users are strictly equivalent, however.
Every thread is infinitely unique. This is why we iterate.