Immunoprecipitation and western blotting are both used to locate a specific protein within a sample and to isolate it. In immunoprecipitation, a specific antibody and agarose beads ( or other insoluble beads) are used to precipitate the protein. In western blotting, SDS-PAGE is carried out and primary and secondary antibodies are used to locate and isolate the proteins on the nylon membrane.
My question is: which technique should be used when? what is the difference between the two? is one of them "better" / does one of them have advantages over the other?