So I'm not sure if some vendors choose to use the weathered and hunting (or green variations and hunting) as interchangable descriptions.
They might, but they would be using the terms incorrectly.

"Dress" and "hunting" are usually specific tartan pattern variations with a different sett from the original, where "ancient", "reproduction", "modern", "muted" and "weathered" are all just color variations of the proper original clan tartan.

There may be some examples out there of hunting tartans that have the exact same sett as the original clan tartan, but in different shades or colors. But that still wouldn't make them necessarily interchangeable with the weathered variations.