Real Traffic provides realistic airplane models, airlines, and schedules. Real Color provides realistic liveries. If you want paint schemes you'll need to acquire one or more Real Color packs.
Although the Real Color packs are produced for each airport, the liveries in a pack can be seen at other airports (assuming there is a plane/model in the schedule). For example, you only have RC for KLAX and it includes a AAL/B738. You'll see color for any airport with an AAL/B738 in the schedule. As a result, if you get a new airport I recommend to play that airport first and if you decide there are too many white planes then buy the RC pack for it. Otherwise, save a few bucks.