A daily trainer is judged on what it does not do. It should not be the reason a run goes badly, it should not need thinking about, and it should still be there in six months. The Pegasus line has been built to that brief for over thirty years, and the 42 changes little from the 41 — which is a feature rather than a disappointment.
The drop is the specification that matters most here, and it is also the one worth reading twice. Nike states 10 mm. RunRepeat, which cuts shoes in half and measures them, records 14 mm. Both figures are published, both are on this page, and we are not going to pick one for you: manufacturers measure to the foam, labs measure to the insole, and a four-millimetre disagreement is common enough that it should change how much weight you put on a stated drop in general. What is not in dispute is the direction — this is a traditional, higher-drop shoe.
Why that matters: a higher drop shifts load away from the calf and Achilles and towards the knee. If you are coming from a low-drop shoe, changing this number abruptly is one of the more reliable ways to injure yourself. Change it gradually or not at all, and if you are switching from an earlier Pegasus, note that the number you are switching from may itself have been a stated rather than a measured one.
On weight the same split appears. Nike quotes approximately 300 grams for a US 10; RunRepeat measured 286 grams on its sample. Either way this is heavy for a modern daily trainer. Weight matters less on easy runs than shoe marketing suggests, but it is a real difference over a long run and it is the clearest argument for looking elsewhere if you race in the shoe you train in.
The midsole is ReactX foam over a full-length Air Zoom unit, and the specification worth knowing about ReactX is durability rather than energy return: it holds its properties longer than the React foam it replaced. Combined with a high-abrasion waffle outsole, that points to a longer working life than the lighter, softer foams in racing shoes, which go flat well before their outsoles wear out.
Fit is the one place to be careful. Nike sells this in regular and wide, and most retailers stock only the regular. If you have had midfoot pressure in Nike shoes before, order the wide fitting or try both before committing.