In JoJo's Bizarre Adventure Part 5: Golden WInd an upgraded form of Stands known as Requiem was introduced. Officially, Giorno Giovanna and Jean-Pierre Polnareff are the only characters shown to gain Requiem Stands. Yoshikage Kira, the main villain of Part 4: Diamond is Unbreakable, may have accessed this upgrade as well, although it has never been confirmed as such in canon.
Reusing the Arrow
Normally, one of two things will happen if a person is struck by a Stand-producing arrow -- they will gain a Stand if they're mentally strong enough or die if they are not. However, if someone who is already a Stand user is pierced, or if their Stand itself is pierced, something quite different happens.
Requiem is achieved when, under certain conditions, a Stand is pierced with the arrow. This causes the Stand's appearance and powers to drastically change. For instance, when Polnareff's Silver Chariot became Chariot Requiem, it changed from a metallic swordsman that could pierce anything to a shadowy, plastic-looking figure with the ability to manipulate souls.
Kira, who is already a Stand user and currently living under an assumed identity, uses an arrow on himself a second time towards the end of Part 4. His bomb-based Stand, Killer Queen, develops a new power known as Bites the Dust, which blows up its target if Kira's identity is revealed, then reverses time by about an hour so that the reveal and explosion never happened. The Bites the Dust bomb manifests as a miniature version of Killer Queen, so despite the Stand's overall appearance not changing, its form does change in a less dramatic way.
New Powers as Needed
When a Stand becomes a Requiem Stand, its powers change according to what its user needs at the time. Chariot Requiem exists to protect the arrow, and its soul manipulation powers allow it to turn attackers' Stands against them, among other effects. Giorno's Gold Experience Requiem can "revert actions to zero", which allows it to negate the time-manipulation abilities of King Crimson and trap its user Diavolo in an endless cycle of death.
Bites the Dust similarly exists to protect Kira's identity and reverse his murder of Hayato Kawajiri, the son of the man he is impersonating. With its power to both eliminate anyone who discovers who Kira is and to reverse time so that he was never discovered at all, Bites the Dust allows Kira to avoid the consequences of his mistake and continue hiding in peace. Like the Requiem Stands, this is a very powerful ability that makes its user much more difficult to defeat.
So, are Bites the Dust and Requiem the same? The main differences between them are that Kira pierces himself rather than his Stand to gain his new power and that Killer Queen's appearance does not change, with Bites the Dust being more of an add-on to what it could already do. Interestingly, Kira's appearance does change when he gains Bites the Dust, his hair changing color and style -- perhaps this is simply a result of the arrow being used on him instead of his Stand. It's not canonically stated, but because of how similar they are, it makes sense to assume that what happens to Kira is an altered or slightly "incomplete" version of Requiem.
