Which feature of chytrids makes them different from the other types of fungi

Unlike other fungi, chytrids have flagellate gametes.

Explanation:

Chytrids are predominantly aquatic, indicating that this kingdom will have its origin in water, such as plants and animals. They have flagellate gametes, which no other fungus presents, suggesting that they have lost this characteristic throughout their evolutionary history.

Like the remaining fungal phyla, chytrids have a chitin cell wall but there is a small group (Hyphochytrios) with cellulosic wall, a unique feature among live fungi.

There is considerable variability in the morphology and ecology of chytrids. They may be freshwater or marine, plant parasites and dipterous insects or saprophytes. Some are unicellular, some are Mycelian cacillites.