What is the difference between Western Blot and ELISA?

Western blotting (or immunoblotting) is a widely used method for protein detection, using antibody-based probes to obtain specific information about target proteins from complex samples. The WB is more of a qualitative method, sometimes as semi-quantitative. It could be utilized for studying the purity and post-translational modification of the protein and provide a relative expression of the protein of interest over other protein. It is an

ELISA (enzyme linked immunosorbent assay) is a rapid and sensitive immunochemical assay designed to detect and quantify soluble biomolecules such as peptides, proteins and hormones. The epitope of interest binds with antibody conjugated to the reporter enzyme. Upon binding, the enzyme catalyzes a colorimetric reaction, which could be measured by a microplate reader. The ELISA can be both qualitative and quantitative. Based on the calibration curve, the concentration of the analyte can be found. However, using ELISA, it is not possible to see the changes of post-translational modifications in proteins.  At the same time, ELISA is preferred in studying the concentration/presence of a target in multiple samples.