In a name

One of my coworkers walks in my office and says "I need a computer named Nancy-812 on the network."

This doesn't sound anything like our naming scheme, so it might be a very old computer or a one off kind of connection. So, I ask him directly "Nancy-812? Is that right?"

"Yup." he responds in a matter of fact tone. Actually, this guy only has one tone and that is it.

"OK." and I start entering the name in the correct field to search.

It is not until this point that he stops and in that classic matter of fact tone says "Oh, wait. It is N-8612"

"That makes much more sense." I say and do the job.

What is the difference between "N-8612" and "Nancy 812"? Say them both to different people quickly.