No fancy packaging:
Plain box product comes in a plain box, OEM or Bulk - in an anti-static wrap.

Accessories may differ:
Accessories that usually come with the retail version may or may not be included.

User's manual may differ:
User's manual may be abridged or not included. Please use Manufacturer's web site for complete manuals.

Software bundle may differ:
Usually those products include drivers, but not include additional software that comes with the retail version of the product.

Technical support from manufacturer may differ:
Usually manufacturers do not offer full technical support to end users on these types of products.
The cost of technical support that you pay for when purchasing a retail version is not included when you purchase OEM, Bulk or Plain Box version.

Warranty period may differ:
Please see the above package information for warranty period, items without warranty information are warranted thru manufacturer