Both examinations use verbal, math and essay sections to establish a student's likely success in post-graduate studies. They are also both computer-based exams that require a few hours to take, with two and a half hours allowed for the GRE and three and a half for the GMAT. As computer-based exams, the tests also allow unofficial scores immediately upon completion. The validity of each test lasts for five years.
While exact score comparisons are difficult, the GMAT is generally considered to be the harder of the two exams. Math and verbal questions on the GMAT are considered more challenging than equivalent questions on the GRE. However, the GRE is seen as more difficult for non-native English speakers as the vocabulary demanded by the exam is less suited toward foreign or non-native examinees.
The GMAT, the older of the two exams, was originally developed by business school deans to predict a student's success during the first year of study, and has proven itself a good indicator of performance. Later, the GRE was developed as the standardized test for post-graduate programs outside of business or other specialized fields, such as medicine or law (which use the MCAT and LSAT respectively).
At one time, both exams were administered by the Educational Testing Service (ETS) which maintained that the GMAT was for use by business schools and the GRE for use by non-business graduate programs. This changed in 2006 when the licensing rights for the GMAT were lost to ACT Inc. To make up for this loss in business, ETS began a push more for the GRE to be accepted by business schools as a substitute for the GMAT, adding in extras such as a questionnaire on creativity, ethics, communication and other personal elements that can't be judged through quantitative testing.
While GMAT remains the more trusted exams by business schools, an increasing number of programs are accepting the GRE as an alternative. Whereas more business schools are now accepting the GRE, the GMAT has not gained the same level of usage by non-business schools.
One of the major draws of students to the GRE over the GMAT is the difference in pricing. Depending on whether or not the examination requires an additional subject test, the GRE is priced, as of March 2011, at between $160 and $205. The GMAT, which comes in only one version, carries the uniform price of $250.
As stated previously, the GRE includes an additional section called a subject test. These are required by some graduate programs, such as biology, chemistry, mathematics, computer science and literature, to determine a student's specific knowledge in these subjects. The subject tests are optional and requirement is up to the discretion of the specific school's graduate program.
Since the GMAT is already limited to business schools, there is no further specialization of the test available.