Although with a similar name and adventurous spirit, the Explorer and the Explorer II models are of major differences. If you’ve ever wondered about this, here are the answers.
In 1953, Rolex released the Explorer replica watch to commemorate one of mankind’s most historic expeditions—Sir Edmund Hillary and Tenzing Norgay’s climbed to the summit of Mount Everest, the highest mountain on earth. The fake watch was suitably named Explorer, the cheap Rolex replica watch featured tough stainless steel construction, a highly legible dial, and a waterproof case, and temperature resistant ability.
In 1971, Rolex created a new watch named Explorer II that was mainly for spelunkers and polar explorers or people who spend a lot of time in the dark or areas with irregular sunlight hours. As such, the Explorer II features an extra 24-hour hand, a 24-hour marked bezel, and a highly luminous dial therefore users could always differentiate between day and night hours regardless of the environment. 
When it comes to function, the Explorer and the Explorer II are different as well. The Explorer is a simple design Rolex model. But on the contrary, Explorer II has a few other functions. First, there’s a date window at 3 o’clock. Then there’s an extra 24-hour hand. On the first Explorer II watch, this extra triangular-tipped hand indicates AM/PM, since it’s synchronized to the main hour and minute hands. With iteration, the Explorer II became a GMT fake watches since the 24-hour hand is set independently from the center hour and minute hands.
The Explorer always comes with a black dial with 3, 6, and 9 markings besides stick/baton indexes. In fact, this dial design is called the “Explorer-style” dial.
As for the first Explorer II, also known as the Rolex Steve McQueen, only has the version of black dial, Rolex provided both black and white dials on all subsequent Explorer II models. Also, the extra 24-hour hand began as orange, then it was changed to red, and on the most recent version, it was changed back to orange.
