The cosmos is the term used to describe the universe in a settled state meaning the exact opposite of chaos. It is a term given to mean viewing or thinking of the universe with a systmatic approach. Using the word cosmos rather than the word universe implies viewing the universe as a complex and orderly system or as a non-chaotic entity.
In studying the cosmos, all of the things which have been discovered or proven about the universe are part of the equation rather than simply seeing all the things which have not been studied. The universe can be overwhelming and mysterious but the cosmos is more settled and contains many facts.