“Like” products are a subset of directly competitive or substitutable products: all like products are, by definition, directly competitive or substitutable products, whereas not all “directly competitive or substitutable” products are “like”. The notion of like products must be construed narrowly but the category of directly competitive or substitutable products is broader. While perfectly substitutable products fall within Article III:2, first sentence, imperfectly substitutable products can be assessed under Article III:2, second sentence.