The interviewer is asking a technical question, which requires you to compare different types of visual models used to analyze data. Knowing the differences between two similar but different techniques used to illustrate the results of data analysis will confirm that you are qualified for this role. Technical questions like this are best answered by comparing the terms presented by the interviewer and possibly providing an example of how they are used in your profession. Your answer should also be brief and to the point to provide the interviewer the opportunity to ask a follow-up question.