Examples please?

When she says the interface is not the solution I believe what she is saying is the the interface is designed based on the solution model. The solution model being a list a requirements whose purpose has been validated by data collected from the people who will use the product.

That was a general example, so now I will give you a more specific web-based one:

You are building a landing page for an e-commerce web service. This is a marketing page for potential customers who may not have heard of your product prior to landing on the page. You want them to sign up for a free trial. So, before you start designing the web page visually, you need a solution model, what needs to be on this page? Some things that you may decide are needed are:

• An explanation of what the product is and why it is needed
• Clear language expressing that the trial account it free
• Testimonials or other social proof that this is a quality service
• A form that collects only the essential data needed to create a free account for the user. This component would be broken down so that you would know exactly which form fields would be used, since the more steps in a form the less likely it will be completed.

Now you have a basic solution model. From here the user interface designing can begin.

So, in summary of this example, the solution model is what should be included in the landing page and the interface is how it is presented to customers.

I hope this helps!