A medium question is technically more accurate description since a section is scored on a 60-90 grade but nobody understands how good Q85 vs. V85 vs. DI85 is, so yes, we need the 600-700 or easy/medium. One issue with 600-700 that's the old GMAT score measurement format so it is quite incorrect to use this band as the GMAT Focus and Classic fall into different segments for 650 vs. 655 score for example.
Anyway here is what each band contains:

And if you are using a book, we have more exact difficulty measurement:
https://gmatclub.com/forum/error-log-fo ... 45984.htmlAttachment:
GMAT-Club-Forum-wz00jzif.png [ 74.5 KiB | Viewed 21 times ]