Multires uses more Memory(RAM and Virtual RAM), because it has to keep vertex information for each level. Also multires isn’t affected by the simplify settings. It also has the Linear subdivision option and is designed with sculpting in mind. The default subdivision uses a slightly different smoothing options which can lead to faces not always being evenly smooth after the faces are divided, which is useful for sculpts that have convex to concave switching. Subsurf will make sharper creases. Most of the time they work exactly the same an both use the Pixar OpenSubdiv libraries.
Basically, yes you could use multires instead of Subsurf.
