If you're using them as general variables (such as X and Y, which is more common, or A and B perhaps), you can't use the same variable for two different things.
If you mean N = "the success" and M = "construction projects", then "N of M" makes sense. But "the success of the success" doesn't.
In any case, I think you mean two separate and different variables. Whether you need an article, and what article you need, would depend upon the sentence.
Would you like to write a few sentences (full sentences) using these constructions, and we'll comment on them. As phrases, they can take an article if you give them one.
Student or Learner