Warning! Spoilers ahead for Iron Cat #2
There are many characters in comics who could be viewed as copies of other characters, but in the case of Marvel's Black Cat, it's been revealed that she's actually much different from DC comics's Catwoman.
Felicia Hardy aka Black Cat is in a bit of a jam currently. In her youth she was the protege of a world-renowned thief named the Black Fox. But she didn't study under him alone. She had a rival named Tamara Blake, who has recently resurfaced and stolen the Iron Cat armor that was created for Black Cat by Tony Stark. Using this armor, Tamara seeks to gain her revenge on Black Cat, whom she blames for the death of their mentor.
In Iron Cat #2 by Jed MacKay and Pere Perez, Tamara recollects her time alongside the young Black Cat when they were still training to be master thieves. Felicia actually grew up with wealth, so she didn't need to steal to survive. Instead, she stole for the fun of it. Crime was considered a game to her, one that she always wanted to win. This is in contrast to Tamara, who took her job as a thief very seriously. She grew resentful of Felicia, whom she viewed as reckless and could endanger them all.
It's ironic that Catwoman would also feel the same way. Because of the many similarities between them, it's easy to believe that Catwoman and Black Cat are essentially the same character. They are both skilled cat-burglars and occasional anti-heroes who dress in black, have "cat" in their name, and have romances with the superheroes who often pursue them. But these similarities are all skin deep. Below the surface Catwoman and Black Cat are far different individuals.
As stated before, Felicia Hardy grew up wealthy and steals for fun and the thrill of it. Selena Kyle aka Catwoman is the exact opposite. She grew up poor and steals for money. In fact, she views herself as a protector of the downtrodden and the neighborhood in which she lives. She has become Catwoman out of necessity rather than any drive towards an adrenaline fueled adventure. She has a duty to perform. In contrast, Black Cat gets off on her role either as a superhero or villain. She doesn't feel like she has a duty or obligation to do the things that she does. Instead, she steals and fights because she enjoys it. In this regard, any fan who takes the time to learn about these characters would know that Black Cat and Catwoman truly are very different.