The Basestar is the equivalent of a Battlestar, a Cylon Raider cannot operate too far from a Basestar. The first picture is from the re-imagined series whereas the second is from the original. The bridge is from the second series. The craft can carry an unknown number of Cylon Fighter craft. They are never too far away from a Resurrection Ship so those killed in battle can be resurrected. In the original series, Count Baltar had his own craft which he used to order the Cylons around.
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