Embedded software types of testing

I am doing some tests with the embedded system software. Currently I am focusing on: 1/ Same input for multiple times then get the differences between the outputs (I don't remember the name of this test). 2/ Different inputs for multiple times (I also don't remember the name of this type too). Can anyone help me how to deal with these types of test such as how to perform them, input generation, or steps to perform them. I am new to embedded system testing. Thank you very much, Best regards, Duy