There is a wealth of info about Indian Classical music (ICM) basics online so I will just share a bit for beginners like myself.
The music of North India is referred to as Hindustani and Carnatic in the South.
Vocal music dominates both but some instruments tend to be in one or the other.
The drone instrument, tambura is in both. It provides the ground for the music to dance!
some Hindustani Instruments-
Tabla, sitar, sarod, rudra veena
Some Carnatic-
Saraswati veena, mridangam , ghatam , violin
The "Raga or "Ragam" is a melodic frame work used for improvisation and composition in both the North and the South. Unlike scales and modes in the music of the West the raga has rules (which are sometimes broken) pertaining to the way it is sung or played. There is a certain order the notes(swaras) are to be followed. If this is not done correctly then the mood or "Rasa" of the Raga is lost.
Ragas differ from the North and South. Some exist in only one or the other while some exist in both but with different names. Lets examine this!
The Raga "Yaman" in Hindustani music is equivalent to the notes of the Lydian mode.
In Carnatic it is called Kalyani.
Here are both. North using sitar and South using veena.
Very different sounding but using the same notes.(The sitar is in D and the veena Eb so even more tricky to compare)