1. A method for detecting defects, comprising the steps of: irradiating and scanning an electron beam focused on an area of a sample; detecting charged particles generated from the sample by the irradiating and scanning of the electron beam with a first detector which detects charged particles having relatively low energy to obtain a first image of the area and with a second detector which detects charged particles having relatively high energy to obtain a second image of the area; comparing the obtained first inspection image of the area with a first reference image to generate a first difference image and comparing the obtained second image of the area with a second reference image to generate a second difference image; detecting an open defect or a short defect from at least one of the first difference image and the second difference image; identifying a location of the detected open defect by processing the first difference image containing the open defect; and identifying a location of the detected short defect by processing the second difference image containing the short defect.