How the earth would be different if there was no moon?

Without the moon, Earth would spin faster. Our day would be shorter. Billions of years ago, Earth spun around on its axis much faster. Our world's cycle of day and night was less than ten hours long. The ebb and flow of the tides are what put the brakes on Earth's spin. The moon and sun together cause the tides. If we'd never had a moon, we'd still have tides, but they wouldn't be as strong. So - if you're imagining Earth with no moon - you have to imagine our day on Earth much shorter than our present-day 24 hours.