What is the difference between the electronegativity of carbon and sulfur?

The concept of electronegativity deals with the power of attraction of an electron to element in a compound.

2.5 = carbon

2.58 = sulfur

Sulfur, having the higher electronegativity, will attract the electrons in the compound slightly more than carbon in the same case.

If you want to measure the power of attraction to single atoms, electron affinity is used.