Quote Originally Posted by ForgottenLore View Post
Can someone provide a reference for this? I just recently re-read the trilogy again specifically looking for this and could only find references to Sauron using Uruks, meaning big orc, not Uruk-Hai.
This is the way I have always understood it:

The only appreciable difference between "uruks" and "uruk-hai", as Tolkien uses the terms, is that "uruk-hai" seems to mostly be used by Saruman for his "fighting uruk-hai" and entailed certain improvements that Sauron had not introduced, such as resistance to sunlight. Otherwise, you're looking at the same basic creature, and any of the larger, more disciplined soldier breed that they both employed could be referred to as an "uruk".

So, I have a tendency to think of the two as interchangeable but there are some differences between them.

I'm not certain, but I want to say that the uruks that Sauron used were his own improvement on Morgoth's orcs, which Saruman then further refined into the uruk-hai.

I think the uruk-hai being a crossbreed between uruks and dunlendings was speculated by Treebeard, and that certainly may be how Saruman worked in those "improvements".