https://www.eurail.com/en/help/interested-in-eurailing/do-i-need-a-eurail-or-an-interrail-pass mentions Eurail Pass and Interrail Pass have the same price:
European citizens can use an Interrail Pass instead, available from Interrail.eu for the same price as a Eurail Pass.
https://www.acprail.com/blog/2010/12/faq-whats-the-difference-between-a-eurail-and-interrail-pass/ mentions a few differences (I removed the difference they mentioned about the network, which I believe is nowadays the same):
The validities, or number of travel days, to choose from is also different for these two passes. Furthermore, InterRail does not offer Regional or Select Passes where Eurail does, but InterRail do offer a larger selection of One Country Passes.