18.353 studies maps and ordinary differential equations, explaining the qualitative properties of solutions, and conditions under which they can become chaotic. 18.354 concerns the mathematical principles underlying continuum systems. Fundamental ideas include averaging, singular perturbations, instability, and turbulence. Sample problems include approximating an integral or finding roots of an algebraic equation. The calculations are usually done with the aid of a computer or calculator.
Topics vary, but have included linear programming.
It is skewed toward applications to real world problems. 18.062J is somewhat more elementary, it treats those aspects of mathematics that are basic for computer science. This is the basic introduction to combinatorics at MIT, though it has few prerequisites, it is distinctly not elementary. This subject deals with the mathematical aspects of the field of computer science. 18.440 is the standard introduction.