A "substantive difference" refers to a noticeable and significant distinction between two things. It means that there is a meaningful contrast or change that can be observed or experienced. Full definition
But what are the major substantive differences between these three versions of the same epic story? (animenewsnetwork.com)
But despite these apparent differences, in practice the experience suggests that there has been little substantive difference in this aspect of the framework. (rba.gov.au)
While there have been substantive differences about how to move forward, we all have agreed that we must find a way to serve that ideal despite the constraints we currently face. (archinect.com)