I was a WordPress PHP developer at the time and I discovered that with Ruby on Rails you have more control over data flow and the Rails routing engine. (interview did not seem to understand what I meant by data flow). I explained from a data flow perspective that Rails allows for custom routes and custom routes with their own actions, unlike WordPress, which I was working with at the time. (Interviewing began wanting to debate me that you cannot compare one with the other). I answered I was not doing a compare and contrast, but walking him through how I went from PHP WordPress to being a Ruby on Rails developer.