The phrase "great disparity" refers to a significant difference or inequality between two or more things. It indicates that there is a noticeable contrast or gap between them. Full definition
80 % of AP teachers agree that today's digital technologies are leading to greater disparities between affluent and disadvantaged schools and school districts. (projectappleseed.org)
Finally, a 30 - country poll shows great disparities among nations. (thetyee.ca)