Two DC heroes with strikingly similar powers are Animal Man and Vixen. Both can emulate the abilities of animals by tapping into the Earth's morphogenetic field -- a mystical force tied to all animal life commonly referred to as the Red.
This is a pretty rare type of superpower, and it sets them apart from heroes with more commonplace abilities like superspeed or flight. Considering the two heroes' similarities, an obvious question arises: which one of them is stronger? A quick dive into their lore will reveal the answer.
Animal Man
Buddy Baker was given the powers that let him become Animal Man when an alien spaceship exploded near him. The character was created by Carmine Infantino and Dave Wood, and he debuted in 1965's Strange Adventures #80. However, Animal Man rose to new fame when he starred in a 1988 Vertigo series by Grant Morrison and by Chas Truog. This series explored what Buddy was like as a husband and a father, even as he grappled with what was expected of him as a hero. He became a vegetarian, championed animal rights and stood against Apartheid. He has been an active member on several different versions of the Justice League.
The Vertigo series explained that Animal Man's powers came from tapping into the planet's morphogenetic field and explored the limits of his abilities. Over the years, he has replicated the color-changing of a chameleon, a fly's reflexes, and the flight of birds, among many other animal abilities. He once regrew his arm after it was ripped off by emulating earthworm biology. That said, Animal Man can't shapeshift, so when he flies, he does not suddenly gain wings. Once, when he became stranded in space, he could not access his powers until a group of Sun-Eaters flew within range of him. He then replicated several of their physical attributes at once and returned home. The New 52 retconned Animal Man's identity, explaining that he had been given powers by the Red to protect his daughter, who was destined to be the champion of the Red. It is unclear how much of this new continuity remains canon.
Vixen
Vixen was created by Gerry Conway and Bob Oskner, and was intended to be the first Black woman to star in her own DC comic. However, this series never came out as the company canceled 24 of their existing or planned comic series in 1978. She eventually debuted in 1981's Action Comics #521 by Gerry Conway, Curt Swan and Gene D'Angelo, where she took on an illegal fur smuggling operation. When Superman tried to intervene, she was able to drive him back by replicating the strength of a bull elephant. Her debut also revealed her civilian identity, businesswoman and fashion icon Mari McCabe. This debut also explained that she received her powers from the magical Tantu Totem necklace she wore, but in time, this would become a focus for her powers, rather than the source of them.
One of Vixen's ancestors was a legendary Ghanese warrior named Tantu who acquired the necklace from the spider god Anansi. This necklace helps Vixen tap into the Red to emulate animal abilities. Like Animal Man, she has copied the strength and flight of birds, and once even used the healing powers of flatworms to regrow her entire body after she was pulverized. She has also been part of multiple iterations of the Justice League and has worked for the secret organization Checkmate.
Who Is More Powerful, Animal Man or Vixen?
While the heroes have a lot in common, there are some things that set them apart. Animal Man received his abilities from aliens, and as such, his powers work in space so long as he is within proximity to another creature. To date, Vixen has never really had such limits tested, so there is no way to know whether her magic is limited to the Earth or Earth-based animals. However, she does not need to be close to an animal. She has also copied the powers of extinct creatures like dinosaurs and even mythical beasts like dragons.
One final detail of note is that Vixen is capable of shapeshifting and can assume specific physical traits of animals while maintaining most of her human form -- something Animal Man can't do. She is clearly the more powerful of the two.