How is this different from Diwali?
Diwali was 8 November 2026 and is past. Kartik Purnima is the full moon that closes the month, Tuesday 24 November, at 14:53 UT. In the north the night is called Dev Diwali: another lighting of lamps, and a bath. The moon table is the astronomy. The panchang is the religious day.
Tamil homes are keeping Karthigai Deepam. Sikhs are keeping Guru Nanak Gurpurab. Thailand is keeping Loy Krathong. The collection does not merge them.