As adjectives the difference between unanimous and overall
is that
unanimous is based on unanimity, assent or agreement while
overall is all-encompassing, all around.
As an adverb overall is
generally; with everything considered.
As a noun overall is
(british) a garment worn over other clothing to protect it; a coverall or boiler suit a garment, for manual labor or for casual wear, often made of a single piece of fabric, with long legs and a bib upper, supported from the shoulders with straps, and having several large pockets and loops for carrying tools.