Hello aspirant, 

You should give your gate exam at first. Candidates should have completed their Bachelor's degree in Engineering/Technology or Master's degree (M.Sc) in any relevant science subject or must be in the final year of the programme. While applying for  GATE 2019, there is no minimum pass percentage in the qualifying degree.The purpose of the GATE exam is to test students knowledge and understanding of their under Graduate level subjects in Engineering and Science.There is no age restriction for the candidates who are willing to apply GATE Exam . An applicants can give GATE unlimited times, but every result of each attempt is valid for 3 years only after its result date. There is no any age limit or a number of attempts limit for the GATE.The GATE exam is of 3 hours duration and contains a total of 65 questions with 10 general aptitude questions worth a maximum of 100 marks, carried out in an online Computer Based Test mode. The questions consist of both multiple choice questions and numerical answer type questions.The advantages of taking the GATE examare varied. ... GATE (Graduate Aptitude Test in Engineering) is also the qualifying test for many PSUs like Power Grid, IOCL etc. So if you want a high paying job with the security of a PSU, GATE is the only option for you.

GRE or Graduate Record Examination is undertaken for admission to Graduate Programmes abroad. Hence, candidates who plan to appear for GRE are required to have successfully completed their Undergraduate course to be eligible for GRE. Students can register for the exam irrespective of age and qualification.Compared to the ACT and the SAT, the GREis typically considered more difficult because, even though the math tested on the GRE is a lower level than the math tested on the SAT and ACT, the GRE has more challenging vocabulary and reading passages, and the math problems have trickier wording or require higher-level 

The Graduate Record Examinations is a standardized test that is an admissions requirement for most graduate schools in the United States. The GRE is owned and administered by Educational Testing Service. The test was established in 1936 by the Carnegie Foundation for the Advancement of Teaching.

Hope this information helped you.