What is an Imperial Presidency, and an Imperilled Presidency? Is it a case of a President being One or the Other?

-An Imperial Presidency is a President with Ineffective Checks and Balances from the other branches -An Imperilled President is a President who does not have enough Power to be Effective -Usually, the President fluctuates from Imperial to Imperriled (or the other way around) as the Term Progresses, or rather is Imperial in one Area, and Imperriled in another (Foreign Policy vs Domestic Policy)