A billion is bigger than a million.
One million is equal to 1,000,000 (six zeros) while one billion is equal to 1,000,000,000 (nine zeros). So a billion is 1,000 times bigger than a million.
One million is written as 10^6 in scientific notation while one billion is written as 10^9 in scientific notation.
To put it into context, imagine you have a million dollars in cash. That would be a significant amount of money for most people, but it would be a relatively small sum in the grand scheme of things. If you had a billion dollars, you would be one of the wealthiest people in the world.