‘Undergrad’, is a 4-year program, after 12th Grade, where students can study a wide range of subjects to begin with. Once they have met the core curriculum requirements, students at most institutions are asked to choose a specific field of study, also known as the major. The final two years are spent taking more courses that are more directly related to your major.
Masters of Science (popularly known as MS) is the choice of maximum applicants across the country. Others graduate programs are MBA, MPH, etc. These are 2 years full time programs which combine first-class teaching and practical industry exposure to prepare graduates for professional work.
The Doctor of Philosophy (Ph.D.) is the highest academic degree graduate students can earn in most fields of study. These students often go on to teach at the college level or pursue research positions. The doctorate degree normally takes 4 to 6 years in the USA and 3 to 5 years in Europe.