My answers and comments.
1 This is really a meeting section for free discussion, not for posting specific technical questions.
2 Simple definitions are usually answered by google. E.g.
Define:enterprise software
Microsoft Office Enterprise version
Such search gives for example:
http://en.wikipedia.org/wiki/Enterprise_software
http://warpspire.com/tipsresources/programming/what-exactly-enterprise-software-really-is/
http://www.capterra.com/enterprise_software_definition
3 In general, enterprise software or version is defined as:
Software that "solves" an enterprise problem
Targets organizations - corporations, government agencies - but not consumers.
Includes function-specific (Accounting, HR, Supply Chain, etc.) and industry-specific (Manufacturing, Retail, Healthcare, etc.) solutions.
4 As regards Microsoft Office, it comes in basic or light form for individual users, containing basic functions s.a.: Word, Excel, PowerPoint, Access, Outlook.
Microsoft Office 2007 Enterprise Pro includes:
Word, Excel, PowerPoint, Outlook, Publisher 2007, OneNote, Groove, InfoPath, Integrated Enterprise Content Management, Electronic Formulas, Communicator.
5 My clarifications:
An enterprise version will be bigger, heavier on resources, more expensive and have more functionality than a domestic user version. Its full utilization would also require more expertise.
I would not advise a private user to install such software thinking that it’s better. It will be less user-friendly and heavier, without offering any advantages to him.