One that seems to make it easier to understand million vs billion is 'if you gave your wife/girlfriend $19,231 a week to spend on a shopping trip with a max of a million dollars she would be back in a year. If you gave her a billion dollars for a shopping trip she would not come back in a thousand years.'
Paraphrasing the above 'if you gave your government $19,230,769 a week to spend with a max of a billion dollars they want more in a year. If you gave them $19 billion a week to spend with a max of trillion they'd again be back in year'.