Just to reiterate a little of, and add a little to, what @gsg indicated, the TEST instruction does a bitwise logical comparison (essentially ANDing them bitwise internally but not storing the result) of two operands and sets the processor flags according to the result of that operation. The OR instruction does a logical OR of the source with the destination, storing the result in the destination and sets the processor flags according to the result. They both affect the processor flags the same way. So when the operands are identical, the behavior is the same. There is no difference in flags. However, when the operands are different, their behavior is then quite different. You can also test for zero with and eax,eax which also affects the flags identically.
