1. Main Sequence Stars: These are the most common type of star, including our own Sun. They fuse hydrogen into helium in their core, generating energy and pressure that balances the inward pull of gravity. Main sequence stars can range in size and temperature, leading to different classifications like red dwarfs, yellow dwarfs, and blue giants.

2. Brown Dwarfs: These are "failed stars" that are too small (less than about 8% the mass of our Sun) to ignite nuclear fusion in their cores. They are much cooler and dimmer than main sequence stars, and their atmospheres are similar to gas giant planets like Jupiter.

While many different types of stars can form from a nebula, these are the two most common and fundamental types.