One thing we're asked all the time here at Spark Templates is how a sponsor is different than a donor. The simple answer to this is that a donor gives money or other support without any expectation of getting anything material in return. And a sponsor gives these same things as part of a formal arrangement in which they DO expect something in return.
This distinction is a very important one.
Donors are "friends" of your organization that are willing to provide support for inherent reasons. They posses a strong personal or philosophical connection with what you are doing and provide their support without any formal expectation of a material return.
Sponsors are business interests or entities that have budgeted cash and in-kind support for organizations like yours because they believe that investing this money will generate a tangible return for them. These organizations may have a personal connection to your organization and may also have a philosophical connection, but their primary motivation for becoming sponsors is to drive more business to their brand. They support you because they believe being ASSOCIATED with you is a net positive for their business.
Before you start on your sponsorship package, you should make sure that what you are looking for are actually sponsors. If you're looking for donors, you approach to building a package will be quite different than if you are looking for sponsors.