There are two types of vessel markers. Circle markers designate the vessel is stationary and the boat marker tells us the vessel is moving.
There are also 15 possible statuses which are indicated with different colors.
With a click on vessel marker the vessel information preview opens in the top-right.
Here you can see every piece of information for selected vessel. If you hover on any of these information a tooltip with short description is shown. On the bottom of this vessel preview is a link which leads to official Marine Traffic website with more information regarding the selected vessel.