Is a superhero just a hero with powers?
According to the famed comic book writer, editor, publisher and producer Stan Lee, "A superhero is a person who does heroic deeds and has the ability to do them in a way that a normal person couldn't."
The ability to perform heroic deeds is sometimes supernatural, innate or acquired. Among the more famous superheroes, Superman is born with his skills (innate ability), Green Lantern and Storm have supernatural abilities, while Spiderman acquired his powers by mutation. However, there are a number of superheroes who have no superpowers. Ironman is the greatest example of that. Tony Stark has no superior abilities than intellect and derives all the powers from his metal suit. Batman is another great example, Bruce Wayne derives all the powers from his combat skills and technology. Hawkeye and Black Widow have exceptional combat skills, yet are equal to any other superhero in the Avenger Universe. There are others as well who fall under the category of superheroes, yet have no superpowers (batwoman, bucky barnes, green arrow, phantom, etc.).
Thus, it is more than powers that decide who's a superhero and who's not. In fact, the ability to do good is what distinguishes them and motivates them to act in superheroic ways.