Here's why:

* Main Sequence Stars: These are stars in their prime, fusing hydrogen into helium in their cores. They are the most common type of star and come in various sizes, with our Sun being a good example.

* White Dwarfs: These are the dense, hot remnants of stars like our Sun after they have exhausted their nuclear fuel. They are incredibly small, roughly the size of Earth, even though they can have a mass similar to our Sun.

Think of it like this: Imagine a beach ball (main sequence star) shrinking down to the size of a grapefruit (white dwarf), while still holding most of the same weight.