Notes: The 6205 was launched soon after the earlier 6204 Submariner model. It was the first Submariner reference to feature “Mercedes hands”, and the first to have the name “Submariner” actually printed on the dial. A few very early editions of the 6205 lacked these characteristics (and as a result, are very valuable), however every Submariner produced since has featured these now-iconic traits. It has the Submariner wording on the dial, however no depth rating is printed. All modern-day Submariners feature both the name and their depth ratings, while the reference 6205’s closest relative, the 6204 lacks both markings entirely.

The reference 6205 is a “small crown” Submariner, and lacks crown guards and first-fifteen minute markers on the bezel.

Mechanism: The A260 was used in the 6202, 6204 and 6205 Oyster series in the 1950s. It is a fairly obscure mechanism compared to some of its mass-produced contemporaries. It is an automatic (self-winding) mechanism. Both the A260 and A296 were developed at the same time. Neither one is superior to the other. They just have different form-factors, with the A260 being designed for slimmer cases than the A296. Both are COSC certified as chronometers.

Family Notes: The Rolex Oyster Perpetual Submariner is a line of sports watches designed for diving manufactured by Rolex, known for their resistance to water and corrosion. The first Submariner was introduced to the public in 1954 at the Basel Watch Fair. The Rolex Submariner is considered "a classic among wristwatches", manufactured by one of the most widely recognized luxury brands in the world, and due to its popularity has become the subject of massive counterfeiting. The Rolex Submariner is part of Rolex's Oyster Perpetual line. See a copy of the 1957 Submariner magazine advertisement.

The Submariner model went into production in 1953 and was showcased at the Basel Watch Fair in 1954. The assigned case reference number of this first Submariner was either 6204 or 6205. It is unclear which model came first; in any event, the two watches are nearly identical. Neither has the distinctive "cathedral" or "Mercedes" hands now so strongly associated with the Submariner line. Rather, both of these early submariners have straight "pencil" style hands. Few, if any, of the 6205 watches bear the name "Submariner" on the dial, a major distinction of modern Submariners. Some 6204 models have the Submariner logo printed below the center pinion, while others have the logo blacked out. It is believed that there were unexpected trademark issues connected with the name "Submariner" at the time the 6204 and 6205 were released, accounting for the inconsistent use of the Submariner mark on these early Submariners. Trademark irregularities notwithstanding, both the 6204 and 6205 are designated Submariner models in Rolex product literature.

From Wikipedia