Black Box can cover white box testing

Hi I am new to SW testing.

WBT - Developer does this, makes sure each line is executed and checks all conditional statement.

BBT - in Black Box, I can do the same thing as intended in WBT, I can input various parameters and check for output, make sure I cover all conditional statements by making test case and also cover loop execution.

What is the real difference between White box and Black Box testing? For me it looks like, do a extensive input, corner case coverage BBT and that is going to be a WBT.