Arabic to English Social Sciences Medical: Health Care

According to Wikipedia, مقياس النظير البصري is the Arabic translation of Visual Analog Scale (VAS):

https://ar.wikipedia.org/wiki/مقياس_النظير_البصري

Can anyone explain the difference between مقياس النظير البصري and المقياس التمثيلي البصري ?

I have come across المقياس التمثيلي البصري on a medical questionnaire, and I am not sure what is meant by التمثيلي here.

Thank you to anyone who may be able to help.