It's a combination of things that make Kanitah upset with the situation, not just pure physical strength. Kanitah knows that he's almost second to none when it comes to pure muscular fortitude.
 
Fury's faster.
Fury's almost as strong as he is, and can use a similar kinetic boost for his punches.
Fury's younger.
Fury's much more aggressive.
Fury's taller and has better reach.
Fury's got much more range than he does, with the blasts and everything.
And to top it off, Fury can fly unaided.