The ESTA is one of the travel authorization systems from any visitors to enter into the US from Visa Waiver Program (VWP) countries. This is one of the ESTA USA Visa Application Online Form programs to develop by US Government.
Electronic System for Travel Authorization is an automated system it provides eligibility of visitors. This application to collects the information about travelers and get answers to the VWP eligibility.
ESTA Immigration USA is an automated system the direct eligibility of visitors to travel 38 countries to visit the United State under the Visa Waiver Program (VWP) and otherwise you may consult ESTA US Embassy. The visitors may stay from 90 days through ESTA in the United States