Here's another paragraph I like from the Cloves AB report:
193. Once the imported and domestic like products have been properly identified, Article 2.1 requires a panel dealing with a national treatment claim to compare, on the one hand, the treatment accorded under the technical regulation at issue to all like products imported from the complaining Member with, on the other hand, that accorded to all like domestic products. However, the national treatment obligation of Article 2.1 does not require Members to accord no less favourable treatment to each and every imported product as compared to each and every domestic like product. Article 2.1 does not preclude any regulatory distinctions between products that are found to be like, as long as treatment accorded to the group of imported products is no less favourable than that accorded to the group of like domestic products. As noted by the Appellate Body in the context of Article III:4 of the GATT 1994:
[A] Member may draw distinctions between products which have been found to be "like", without, for this reason alone, according to the group of "like" imported products "less favourable treatment" than that accorded to the group of "like" domestic products.389(original emphasis)
