What is the main difference between adaptive radiation and other forms of speciation?

The main difference between adaptice radiation and other forms of speciationn is : Adaptive radiation happens over a relatively short time.
In natural process of speciation, the perfect mutation could occur within millions of years. In adaptive radiation, the mutation could instantly happenes not long after the radiataion process

This type of galaxy is an approximately ellipsoidal shape and a smooth, nearly featureless image. they are the largest single star systems, in the universe and are built by the collisions of many smaller galaxies.