1. Execution Flow: TestNG allows parallel execution of test cases out of the box using configurations in the testng.xml file, while unittest executes tests serially by default, requiring additional effort to implement parallel execution.

2. Annotations: TestNG provides a wide range of annotations such as @BeforeTest, @AfterTest, @BeforeSuite, @AfterSuite, etc., enabling better control over test execution and setup/teardown actions, whereas unittest offers limited built-in annotations like @setUp and @tearDown.

3. Reporting: TestNG generates detailed HTML reports with information on test execution results, timings, failures, errors, etc., making it easier for users to analyze the test outcomes, while unittest lacks built-in reporting capabilities, requiring additional plugins or tools.

4. Parameterization: TestNG supports parameterization of test methods by providing @DataProvider annotation to pass data values to tests, allowing for repeated execution with different inputs, whereas unittest lacks a built-in mechanism for parameterized testing.

5. Dependencies: TestNG allows test methods to be dependent on each other using @dependsOnMethods annotation, ensuring the order of test execution based on dependencies, which is not readily available in unittest without additional customization.

6. Grouping: TestNG enables grouping of test methods using @Test(groups = "group_name") annotation, providing better organization and concise execution of specific sets of tests based on defined groups, which is not as straightforward in unittest.

In Summary, TestNG offers more advanced features such as parallel execution, detailed reporting, extensive annotations, parameterization, dependencies, and grouping compared to unittest, which has simpler functionalities and lacks some of these advanced capabilities.