The alternate-universe Gwen Stacy who becomes Spider-Woman is commonly known as Spider-Gwen. She comes from Earth-65, a reality where Gwen—not Peter Parker—is bitten by a radioactive spider and becomes her world's spider-powered hero.
The character debuted in Edge of Spider-Verse #2 in September 2014, created by writer Jason Latour and artist Robbi Rodriguez. Her origin deliberately reverses the familiar Spider-Man setup: Peter Parker remains an ordinary student, while Gwen gains powers such as superhuman agility, wall-crawling, spider-sense, and web-shooters.
“Spider-Gwen” became the character's best-known nickname, especially after her solo series began in 2015. In the comics, she has also used Spider-Woman and Ghost-Spider. Ghost-Spider became particularly useful when Gwen traveled to Earth-616, where Jessica Drew already uses the Spider-Woman identity.
A common mix-up is assuming this is the same Gwen Stacy who dated Peter Parker in Marvel's main continuity. Earth-616 Gwen was not Spider-Woman and died in The Amazing Spider-Man #121; Spider-Gwen is an alternate version from Earth-65.