Are you confusing your donors with a bureaucratic category that makes no sense and doesn't matter to them?
You might be if you're raising funds under the flag of the foundation that's the fundraising arm of your main organization.
There are plenty of reasons to organize yourself this way. But none of them are important to donors. If you're communicating in a way that forces them to understand that your foundation is in fact a separately run organization, you are keeping the confusion alive.
Say you're with an organization called "Feed the Penguins." Your logo might look like this:
So far, so good. But if you're like some fundraisers, It's the Save the Penguins Foundation that's communicating with donors. And the foundation has its own logo that emphasizes the separation:
Sometimes the foundation has its own tagline that widens the gap. Instead of a cause-oriented statement like Never let a penguin go hungry, it's Supporting the work of Feed the Penguins.
Donors don't give because you're a foundation. They give because of the cause. The foundation means little or nothing to them.
Downplay the foundation. In your logo and in your language. Give donors "direct" access to the cause they care about.