brake booster vs. hydraullic accummulator

[Ahmad Helal]

what is the diffrence between the 2? how do I know if one is failing
versus the other...what are the symptoms? I assumed that my brake bomb
went bad because i have no assited power...i can't stop in an
emergency...if i slam on the brakes for an emergency there is a weird
metal scrapping/taping noise...and the brake pedal vibrates hard....I
was about to order a brake bomb when I noticed they had a listing for
the brake booster....so now i am just confused