Automatic Watches are powered by the everyday movement of your wrist. The movement is converted in to energy that applies tension to a wound mainspring. These watches do not need to be charged or manually wound and do not require sunlight to work.
Eco-Drive watches are Citizen's version of solar powered watches. These watches take charge from almost any kind of light. This makes them extremely useful in almost any environment. They require no need to be wound or to have their battery replaced. Simply expose the watch face to a light source and the watch will be charged over time.
Mechanical watches are traditionally wound via the crown. This winds up the mainspring mechanism inside and the watch is powered by the stored up energy. These watches need winding every so often to keep the energy needed to keep the movement going.
Quartz watches are by far the most common type of watched. The movement is simply powered by a battery meaning that the battery must be changed if the watch runs out of power to function.
Solar watches are similar to Eco-Drive. Solar simply means the watch face draws power from light meaning that the watch is charged all of the time unless place in an area with no light. Solar watches keep their charge for a limited time so will need sun light intermittently.
Very similar to automatic watches kinetic watches work in the same way, however kinetic watches store power for much longer because the energy is converted in to electricity and stored in a battery. This movement is considered a half way point between mechanical and quartz. The battery of a kinetic watch will need replacing far less often than a quartz watch.
Understanding Watch Water Resistance
Watches are often classified by watch manufacturers by their degree of water resistance which, due to the absence of official classification standards, roughly translates to the following (1 metre ≈ 3.29 feet)
Water Resistant: 3 ATM or 30m
Suitable for everyday use. Splash/rain resistant. NOT suitable for showering, bathing, swimming, snorkelling, water related work and fishing.
Water Resistant: 5 ATM or 50m
Suitable for swimming, white water rafting, non-snorkelling water related work, and fishing.
Water Resistant: 10 ATM or 100m
Suitable for recreational surfing, swimming, snorkelling, sailing and water sports.
Water Resistant: 20 ATM or 200m
Suitable for professional marine activity, serious surface water sports and skin diving.
Water Resistant: Diver's 100m
Minimum ISO standard (ISO 6425) for scuba diving at depths NOT suitable for saturation diving.
Water Resistant: Diver's 200m or 300m
Suitable for scuba diving at depths NOT suitable for saturation diving.
Water Resistant: Diver's 300+ m
Suitable for saturation diving (helium enriched environment).