There was a period of decades where differentiation was made with comics (especially on the cover) about if they were meant to be sold in comic stores (direct market) or at newsstands, drug stores, and so forth (newsstand). At one time, newsstand comics outnumbered direct market copies, but for a lot of years--as the market for comics outside of comic shops shrunk--newsstand variants became less common to outright rarely published. Some people like to specifically collect newsstand variants and depending on the era they are from and their rarity, newsstand variants can command a bit extra value.
CGC, the most popular grading company, has rarely acknowledged newsstand variants unless there is another thing special about them (like a unique price variant). The biggest grading competitor, CBCS has noted newsstand variants for some time, making them sometimes the preferred company if someone really wants to highlight a comic is a newsstand variant. Well, CGC has finally gone and done it where they'll acknowledge on their slabs if a comic is a newsstand variant. It's about time!
A part of me is happy CGC is finally doing this and another part of me wonders if they know it'll get them some extra funds as plenty of people who already got their comics graded will now send them in for a new case that denotes the newsstand variant--and pay a fee for it. Still, I guess we shouldn't like a gift horse in the mouth. Oh, it is also worth being aware that special, "Multipack," comics will be noted too, although that's arguably an even smaller niche than newsstand collectors. CGC took their time getting to the point of actually noting all newsstand variants, but at least now they're starting to do it.