In our courses, we are often asked what the difference is between the Heuristics and the Interaction Principles, as they seem very similar at first glance and both serve roughly the same purpose.

To begin with, it is important to know that the Interaction Principles are the revised version of the Dialogue Principles, as they were still open to expansion. For example, the learning facilitation principle was unnamed learnability, or the individualizability principle was subordinated to the controllability principle.

A precise definition of the interaction principles can be found in the latest version (2020) of ISO 9241-112 and ISO 9241-125.

What is the difference between interaction principles and heuristics?
Basically, the two lists differ from each other in their origin. Interaction principles are defined in ISO 9241, while heuristics were established by Jakob Nielsen. While interaction principles are defined as general design guidelines, heuristics are more like rules of thumb to achieve design principles.

So which is better?
If we look at heuristics and interaction principles for the first time, heuristics seem to be easier to apply to most people. However, we cannot directly say that heuristics are therefore better than interaction principles. Interaction principles are more concretely defined and contain more sub-items which can be used as guidelines. In comparison, Nielsen's heuristics are more like an own interpretation of the interaction principles, with different emphasis.

So the question should not be "Which is better?" but "What do I apply and when?". If we want to get a quick overview of the usability of an interactive system, the heuristics are recommended, because they allow us to quickly identify usability problems. For an exact analysis the interaction principles are better suited, because we have here more exact definitions, with which we can specify the errors.

The two lists are also not the first design guidelines in interaction design. A predecessor of these were, for example, the 8 golden rules of interface design by Ben Shneiderman, which, if you take a closer look at them, have many similarities with the heuristics and interaction principles.

In conclusion, I can only recommend you to have a good look at both lists before you compare a system with them and decide on the basis of that which is better suited for your purpose.