ED vs FL glass

Hi, I am currently doing a research project for college (UK), comparing reflector, refractor and SCT optical systems. In this paper, I’m trying to cover all the physics and mathematics behind each system.
I am currently researching the differences between Extra-Low Dispersion glass and Fluorite glass in refractor telescopes, as I cant find many resources online that specifically outline difference and advantages/disadvantages other than Fluorite glass coating more.
I was wondering if any of you could help me here.