What is the difference between functions and features?

John Simpson and I are spending this week working on a new service which we will introduce later this year (stay tuned for details!). During the course of our conversation, a question arose: what's the difference between functions and features?

I must confess that I found it difficult to articulate a response, so I turned to the ever present and trusty Google to show us the way. One site told us that "features generally refer to physical attributes or specifications of any thing. Functions are what the thing does or is useful for." I'm not sure this is all that helpful, though I believe we were able to get a better grip on it.

A function does something; features are characteristics or qualities of the function, or perhaps how it does what it does.

When assessing software, should buyers look at functions, features, or both? I would think that the focus would be on functions (what you're looking for the system to do for you), as these are fairly easy to identify. Features may vary from vendor to vendor, though functions may be almost universally available. And so, you might consider the features of one vendor versus another, as a way to decide which you prefer.

Care to share your views on this? Please do.