What is the difference between a design-time and a runtime framework, as in "Oracle ADF is a Java EE design-time and runtime framework"?
The distinction is between design time and run time, not frameworks. The fraweworks are for both of these functions.
Design time means during code and UI design, when one is writing code and using graphic designers to design a UI.
Run time is when the application is actually running.
The framework assists in both of these distinct phases.