"Regional variations" refers to differences or distinctions that exist in various geographic areas. It means that something can be different or unique depending on the specific region or location you are referring to. Full definition
Models agree on the qualitative conclusion that the range of regional variation in sea level change is substantial compared to global average sea level rise. (ipcc.ch)
Such flexible factories would allow for regional variations of products and could deliver a much wider range of choice. (steaminfusion.oalgroup.com)
Three previous studies found significant regional variations in diagnosis patterns. (sciencedaily.com)