title: Prolog. Structure(complex term) vs predicate, i dont really get the difference
body: <p>I'm new to prolog and i cant seem to understand the difference between a structure and a predicate.
  Is there really any difference?</p>
  
  <p>While digging around i found that some people consider
  <strong>f(X):-a(X)</strong>  to be a predicate and some consider
  <strong>jealous(X,Y):-loves(X,Z),  loves(Y,Z)</strong>  to be a structure (or a complex term). They look pretty much the same to me.</p>
  
  <p>Somebody care to explain?</p>