Navratri is the nine-day Hindu festival that has immence religious significance to Hindus. It is celebrated five times a year — Vasanta or Chaitra Navaratri, Ashadha Navaratri, Sharad Navaratri, Paush Navaratri and Magha Navaratri.

There are significant differences between the two.
While Chaitra Navaratri falls between March and April, Sharada Navaratri takes place during September-October

The Chaitra Navarati marks the beginning of the Hindu new year as per the Luni-solar calendar and is more prominently celebrated in the Northern and Western parts of India.

Another mythological legend associated with Sharada Navaratri is that Lord Rama worshipped all nine forms of Goddess Durga in order to gain power to defeat Ravana. The tenth day is known as Dussehra when Rama rescued Sita and brought her back home.

During Chaitra Navaratri, all nine forms of Goddess Durga are celebrated on each day.
Southern India celebrates Sharada Navaratri by worshipping Goddess Laxmi and Goddess Saraswati.

People fast on all nine days for both the Navratris and all days are considered extremely auspicious.