GRE
The GRE is a 3-hour and 45-minute test that consists of three sections: Verbal Reasoning, Quantitative Reasoning, and Analytical Writing. The Verbal Reasoning section tests your ability to understand and analyze written material. The Quantitative Reasoning section tests your ability to solve math problems. The Analytical Writing section tests your ability to write a well-organized and well-reasoned essay.
GMAT
The GMAT is a 3-hour and 30-minute test that consists of four sections: Verbal Reasoning, Quantitative Reasoning, Integrated Reasoning, and Analytical Writing. The Verbal Reasoning section tests your ability to understand and analyze written material. The Quantitative Reasoning section tests your ability to solve math problems. The Integrated Reasoning section tests your ability to analyze data and draw conclusions. The Analytical Writing section tests your ability to write a well-organized and well-reasoned essay.
Comparison
The GRE and GMAT are both challenging tests, but they differ in some key ways. The GRE is more heavily weighted towards verbal reasoning, while the GMAT is more heavily weighted towards quantitative reasoning. The GRE also has an analytical writing section, while the GMAT has an integrated reasoning section.
Ultimately, the best way to decide which test is easier for you is to take a practice test for each test and compare your scores.