Hello Sakshi. I would like to tell you that SAT exam is taken by students who are looking to pursue their undergrauation in United States or Canada. The undergraduate schools of these two countries accepts SAT score. Whereas GRE is taken by students who wish to apply for Master degree programs in US and few other countries. You can mention the level of study you want to opt for and the preferred country of study so that I can be more specific. I hope you found this answer helpful. Good luck.