Enterprise Customers

When I did my internship with intel as a junior sys admin, my role was to support the developers and engineers locally on site and across EMEA, they would be referred to as my customer, basically it could be anyone that is dependant on you. The term was a bit alien to me at first, as yes, if you weren't in the know, you most likely assume a customer is someone that buys something from a shop. :-p

Im sure there is a better explanation

Just to add on this, both of them are fairly non-specific terms, IME. For example, Tier 1 banks would certainly class as enterprise customers to a software vendor (and as a result many financial vendors would be exclusively enterprise), but I've seen a company use enterprise to refer to any multi-site install, ranging from the small (sometimes just 2 sites, head office and remote) to the fairly large (200+ sites in multiple countries) setup.

For others enterprise may refer to a standard of availability/uptime/redundancy/etc., or alternatively volumes of data processed by a system. It might also be that they use JEE for software development, and automatically think enterprise because it's in the name. Software customers is a bit more self-explanatory, but still could refer to internal or external dependents.

So, clear as mud!