Many of you wonder the difference between GMAT and GRE. While you can read the discriptions and compositions of each exam on their websites, basically both exams are something that those who are applying to graduate programs have to take. GMAT is often times required by business schools, especially for their MBA programs while GRE is for other fields such as Economics, English, history, etc. While there may be exceptions (please check with each school), most business schools accept both GMAT and GRE for your application.
This is a very hard question to answer. I have talked with many PhD finance coordinators, and I have some mixed feeling. I cannot simply tell you that which is better. So... let me bring up some points, so that you can think about it and decide what to do. At least the easy one is if you are planning to apply to not only finance programs but also economics programs. You have no choice. You have to take GRE. Most Econ programs do NOT accept GMAT.
Now how about those who are applying to only finance? This is where my mixed feeling comes in. This is because the score reports are different from GMAT and GRE. GMAT reports the aggregate score (both quant and verbal) while GRE reports quant and verbal sections separately along with the aggregate score. It seems like, based on the information I received from Dr. Jim Brau that if you want to go to top 10 schools, you should take GRE and get a perfect score on the quantitative section (which is 170). One of the top 10 school's finance professor said, "If the quant GRE is not 170 (perfect), we don't consider." So if you are looing into top-10 schools, take GRE may be the right choice for you. Of course, you have do well enough on verbal, especially if you are an international student. Recently, many PhD programs are having hard time to place international students in the U.S. This is due to their lack of communication skills. Many schools nowadays consider your verbal skills.
If you are decent at quant and actually good at verbal, your choice may be GMAT. While GRE quant is easier, verbal of GRE is is much tougher than GMAT verbal. Obviously it is because English, communications, etc. majors take it. While GMAT report is aggregate score, you still have to report scores for quant and verbal as you apply. Again, what you want is you want a strong enough quant and at least decent verbal.
If you are an international student, you may have a better chance to get into a good school with GRE with a high enough TOEFL score. Many people who look at GRE score understands that GRE verbal is hard. While if you do not do well enough on verbal, that will actually shrink your chance to have an interview, you can always use TOEFL against your GRE verbal score that you can communicate fine. Perhaps, for this purpose all schools require you to take TOEFL and score very well unless you have a degree in an English speaking country. If you take GMAT, you may have a hard time to score 700+, which you will need.
While I touched on some of the target scores, let me summarize here. This is based on Dr. Vorkink and Dr. Brau's information.
GRE
170 on GRE Quant if you are applying to the top schools (top 10)
167+ on GRE Quant if you are applying to 1st tier/top of 2nd tier schools (top 30)
165+ on GRE Quant if you are applying to the second half of 2nd tier schools (top 50)
GMAT
780+ on GMAT if you are applying to the top schools (top 10)
720+ on GMAT if you are applying to 1st tier schools
700+ on GMAT if you are applying to the most of the second tier schools
650+ on GMAT if you are applying to the second tier schools with strong application other than GMAT
GMAT/GRE is an important part of applications but it is not the only part of the applications. Some schools may not weigh the test scores if you have good research experience and have a strong GPA. At the same time, some schools may not even look at your application if your GMAT score is not 700+ or 85 percentile on GRE quant. For example, I did not have 700 on my GMAT. I applied some school that is probably top of the third tier school rejected me without interviewing me because of my GMAT score while some mid to high 2nd tier schools extended interviews with me and even offered me a position. Again, some schools use the test score as cutoff while others look at overall application with mild test score cutoff.