Boil vs cyst
A "boil" is simply a skin abscess
where a bacterial infection has caused a collection of pus
The pus needs to be removed/drained. A cyst is usually the result of a blocked skin pore. The cyst material is usually the normally sloughed off skin cells that cannot simply float away. The collect within the cyst. Cysts do not always need to be treated unless they continue to grow get infected.