Difference between Top-Down Testing and Bottom-UP Testing

NO	Top- Down Testing	Bottom-UP Testing
1	Top-Down testing conducted from main-module to sub module.	Bottom-Up testing conducted from sub module to main module.
2	If sub module is not developed a temporary program called Stub is used for simulate the submodule.	If main module is not developed a temporary program called Driver is used to simulate the main module.
3	Top -Down testing good if major flaws occur toward the top of the program.	Bottom-Up Testing good if major flaws occur toward the bottom of the program.
4	In this test condition difficult to create.	In this test condition easy to create.
5	Observation of test output is more difficult.	Observation of test output is easier.