Now, I have little knowledge about Ganesh chaturthi so I shall skip that part.
Navratri is a very important Hindu festival and is celebrated all over India under various names. We Hindus rest our faith in the Adi Shakti and we worship her in different swarups. Therefore we celebrate the same festival differently as per our own traditions. What we do on that day is not important but how we rest our faith on the same day and on the same deity is the importance of this festival.
In each part of India there is one form of the Devi which is the Isht devi of that region. Its the same Adi Shakti. What is Navratra ? Navratraa is the worship of nine forms of Mother Durga. Therefore it is not different from the logic of Durga Puja. Only Durga Puja is restricted to the Mahishasurmardhini rup pf MOther Goddess. Traditionally, Devi paksha begins from the day Navratra begins. It is as auspicious to as it is to the Gujaratis , Marathis or any other community who follow the Navratra traditions.
During the Chaitramasa Navratra, the Bengalis celebrate Basanti Puja which is the same Durga Puja done during the Vasant Ritu.
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