Various types of building-related materials and products are often described as being "architectural". I have seen windows, doors, roofing tiles, etc. all described this way.
One possibility is that this is just meaningless marketing gobbledygook meant to convey an impression of high quality.
Or it might have real meaning, but not necessarily a consistent meaning in all cases.
But if there is a real, meaningful definition that would help navigate through myraid product choices - what is it?