i think audit report is the umbrella term which state the auditor’s independent expression of opinion.then opinion is the content information which state how the auditor weighs the material misstatement of F.S,whether it was presented true and fair view.Unmodified is the auditor’s report which have no critisism of F.S but with some notes of warnings which are must read notes.While modified is where the auditor find some material misstatement on how the evidence was compiled.Therefore,it will show some critisism which makes the auditor to give qualified opinion , e.g report do contain material misstatement