Is Dev Deepawali the same as Diwali?

No — Dev Deepawali is a distinct festival from Diwali, though both involve the lighting of diyas. Diwali celebrates the return of Lord Rama to Ayodhya and falls on the new moon of Kartik. Dev Deepawali falls fifteen days later, on the full moon of Kartik, and specifically celebrates the gods’ descent to bathe in the Ganga at Varanasi. The two festivals are related in spirit but are separate in mythology, ritual content, and observance.