Though the two DC Comics super-heroines may share similar capabilities, there are 5 things that Power Girl is much better at, and then there are 5 things that Supergirl can only do. Separately, the two Kryptonian heroines have an individual trait that makes them unique and different from one another. With their family heritage related to Superman, Power Girl and Supergirl have been able to escape his shadow and constantly prove themselves, time after time, that they are a truly powerful force not to be messed with. And when the stakes are high and the day needs saving, whatever makes them special actually brings out their best.
Everything you know about Supergirl and Power Girl starts off with the doomed planet of Krypton. Just before the entire planet is about to explore, Kara Zor-L, aka Power Girl, and Kara Zor-El, also known as Supergirl, are given a second chance at life as they find salvation from inside a rescue spaceship. As their spaceship lands directly onto Earth, the two orphans then discover they have much to offer to their new home. Just like their famous cousin, the two Karas share the most powerful abilities of strength, vision, and flight.
10 Electromagnetism (Power Girl)
Because of her Kryptonian physiology, the cellular structure within Power Girl is much denser and biologically adaptable. From her bio-cellular matrix, her specialized internal tissues are able to store the energy emitting from the sun. Because her metahuman body can interact with charged particles, Power Girl is able to store that absorbed energy and hold it to her body's powerful electromagnetic field.
Thanks to being from an alternate universe, this is why Power Girl's electromagnetic capabilities make her far more effective in battle than Supergirl. These electromagnetic enhancements add so much to the physiology that Power Girl was born with.
9 Space Flight (Supergirl)
Though Power Girl is able to defy gravity, lift off from the ground with ease, and fly off into the sky, she actually needs to breathe while in outer space. Because her lungs have to breathe, the Earth-2 super-heroine needs to have an available source of oxygen before leaving a planet.
Traveling from Earth to other planets also takes a toll on Power Girl's strength, as she needs to rest and sleep from the long voyage. Thankfully, Supergirl doesn't have to worry about the lack of oxygen in space, or else she would also suffer from disorientation and fatigue.
8 Immunity To Kryptonite (Power Girl)
Many times in the comic book stories, Lex Luthor has been able to demonstrate his strength and exert his dominance over Superman by simply showing off his Kryptonite ring. Due to the crossover events of Crisis on Infinite Earths, it has been established that Kryptonite can only affect those who come from the same reality.
Because she comes from another earth, Kryptonite has no weakening effect on Power Girl's powers. It would make sense Superman would rather call upon Power Girl, and not Supergirl, in case he needs help against Luthor's glowing green ring.
7 Solar Flare Power (Supergirl)
During The New 52 era, Supergirl was granted a new solar flare power that really comes in handy when being surrounded by super-villains. Because she has the metahuman ability to store the energy from Earth's yellow sun, Superman's cousin is also able to release her solar power into a devastating effect.
When Supergirl decides to unleash her solar bomb, even Wonder Woman has to run away fast and take cover from the massive explosion. As her body temperature rises to unbelievably high levels, Supergirl ends up turning herself into a living and breathing torch.
6 Muscular Strength (Power Girl)
In many iterations of Supergirl, Kara is mostly portrayed with the physical body type of a teenager. Supergirl still has lots to learn in her teenage years, which is why her muscles aren't so well-defined. When Power Girl escaped Krypton and her spaceship landed on Earth, this is where her origin story took a different turn.
Earth-2 Kara was actually trained and raised by Superman and his faithful wife, Lois Lane-Kent. Because of her maturity, Power Girl has a much more muscular and athletic body shape. Power Girl just has to flex her muscles to show how much stronger she is than Supergirl.
5 Shapeshifting (Supergirl)
Though Supergirl has been known as Kara to the entire DC Universe for many years, John Byrne revamped the female superhero for some time as Matrix. Grown in a science lab, the artificial life-form had the memories of Superman's cousin and the face of Lex Luthor's one true love.
In the aftermath of The Death of Superman, Clark Kent needed to prove to the world that he was still alive, but was missing during Doomsday's rampage. Thanks to Matrix's shape-shifting powers, she was able to look and sound like Clark himself, making the lie genuinely believable to others.
4 Hand-To-Hand Combat (Power Girl)
Supergirl isn't really known for her fighting skills, especially since she can use her breath to freeze objects and unleash her heat vision when necessary. Power Girl stands out because of her advanced techniques in combat training.
In the two-part story arc in Wonder Woman #40 and #41, Power Girl ends up getting into an epic throwdown against the princess of the Amazons. At short range, Wonder Woman and Power Girl traded punches and kicks during their physical confrontation. Showing off her strength, Power Girl took one swing, punched Wonder Woman, and sent her all the way to Canada.
3 Red Lantern Ring (Supergirl)
During the crossover event between Supergirl and Green Lantern, Kara's coming-of-age tale took an unexpected turn when she ended up getting a Red Lantern ring. In "The Red Daughter of Krypton" storyline, Kara became a natural fit when she joined The Red Lantern Corps. The red power ring promises the welder would have unfiltered and unchecked rage.
As a Red Lantern, Supergirl was consumed by her inner rage, which she had repressed and struggled with after being stranded on Earth. With great rage taking over her heart, Supergirl fueled her ring as she fed off her every impulse.
2 Genius Intellect (Power Girl)
Because she is more mature and grown-up, Power Girl knows how to use her intellect better than Supergirl. In her origin story, Earth-2 Kara understands data and figures better because she was raised by an artificial intelligence.
When Earth-2 Kara puts on her red wig, the rest of the world knows her as Karen Starr, the CEO of Starware Industries. Excelling in her business and negotiation skills, Karen is able to finance her own lab and come up with technological advancements. Unfortunately, Supergirl doesn't have a business of her own and isn't quite as tech savvy to stay ahead of the competition.
1 Acid Spit (Supergirl)
After becoming a prominent member of The Red Lantern Corps, Supergirl took a dark and moody turn as her rebellious teenage angst defined her. Kara gained access to a variety of new powers, including spitting acid from her mouth. This is probably one of the grossest powers a superhero could ever have, but it does come in handy during a surprise attack.
As a Red Lantern, Supergirl vomits from her lips a disgusting projectile sludge containing an explosive mix of petrol and acid. Imagine having this red goop all over you, burning straight through your skin!