They share a name and an exploration spirit, but solve different problems: the Explorer is the purest three-hander in Rolex's catalog, no date or complications; the Explorer II adds a 24-hour hand built to tell day from night without natural light. The choice comes down to which complication you actually need, not which one is 'more'.
A 36mm Oystersteel case, no date or Cyclops lens, Calibre 3230 with ~70 hours of power reserve and Superlative Chronometer certification. It's the closest reference to the original 1953 Rolex: total legibility, zero complications, a compact size built to be worn without a second thought.
A 42mm case, Calibre 3285 with ~70 hours of power reserve, and the family signature since 1971: an orange 24-hour hand fixed to local time (not independently adjustable — not a true GMT) read against a fixed 24h graduated bezel. It was built for cave explorers and polar expeditions who needed to tell 3pm from 3am without seeing the sun.
36mm versus 42mm is a substantial proportional difference — bigger than any other spec gap between the two. If you want a discreet daily watch, the original Explorer's compactness stands out, increasingly rare in Rolex's current sport catalog.
Pick the Explorer (124270) if you want the purest, most compact three-hander in the catalog, nothing to learn or adjust. Pick the Explorer II (226570) if you genuinely need to tell day from night without a visual reference — or simply prefer a 42mm case with more presence. Neither has verified market price data in Cazador yet.