What is the difference between an abstract and an introduction for a scientific research poster/report?

What is the difference between an abstract and an introduction for a scientific research poster/report?

Abstract is the portion where u describe ur work very briefly,like what u did in the experiments and what u have concluded with the paper. Introduction means it is the introduction of the work,like why u have selected that topic. for example if u are studying about antimicrobial drugs,then in the abstract,u will write what is the drug used for your study and how it is active against certain microbes.but in introduction u have to mention, what are antimicrobial drugs and previous people conclusion about the drugs,existence of certain diseases which that drug can cure.....