Welcome to the forum! Typically the imported natural veg-tan leather is much lighter in color. They add additional chemicals during the tanning process to speed it up. It is typically less expensive than, say, the US tanned leather. You will find that tanneries such as Hermann Oak and Wickett / Craig leather has a tannish color to it and appears to be much richer. The imports are normally very slick on their hide surface, where the others will have a little more texture. In my early days, I purchased the imports to save a little money. It is fine for small projects and you can make it work for carving and stamping. When I took the plunge into the better leather, it was truly obvious in how it worked when carving/ stamping vs. the import.
In a nut shell, color really doesn't determine the quality, it is more about the tanning process. Also, if leather is stored where UV rays can get to it, that will darken the leather as well. Hope this helps.