Walnut can vary from very dark brown or brown-red, to light honey and even yellow gray.
The main light/dark variations you see are usually the differences between heartwood and sapwood. Many people don't know anything but dark walnut exists because many companies go out of their way to eliminate or avoid it.
Not here, we accept all varieties. In many cases I will try and categorize the different types and tones, but you can always message me if you'd like a particular type on a particular product.
You can see this really easily when you go to the source: