Carnatic music tends to be more structured and pre-meditated. It uses melakartas which are made up of a collection of rāgas (an ordered collection of tonal pitches as a basis for improvisation, most akin to musical modes). Carnatic works often include notated poems on themes of worship and philosophy. Hindustani music was more effected by external influences, especially Arab and Persian. The music centres around the idea of improvisation which starts with a core idea and then expands. Despite the distinct styles, Indian music can commonly be identified by a heavily melody-influenced structure that incorporates improvisation. You will often hear three clear parts in the music: melody, rhythm, and a drone. Some recognisable instruments are the sitar (a long-necked string instrument that is plucked), the sarangi (a bowed, short-necked string instrument), the tambura (like the sitar but longer and typically plays a drone), the tabla (a pair of small drums) and the santur (a dulcimer intstrument where strings are struck with a hammer).