A raga is outlined by a scale, typically consisting of 5-7 notes in Carnatic music. However, the scale is just the skeleton; the appropriate gamakas are also crucial. Typical phrasing is also important in delineating a raga.
There are 72 parent ragas in the Carnatic melakarta system, each with a full set of 7 notes, and many more ragas with fewer notes that are derived from these.