There are a few similarities between the American and French Revolutions. Some that I found were...
Britians treasury was drained so they taxed America and angered the colonists, similar to the French treasury being low, so they declared war on other countries to try to refill the treasury.
Both the French and American Revolution had their own declarations and constitutions written.
Both countries won their revolutions.
Each countries king was the cause of the revolution. (King George III and King Louis XIV)
Both countries were influenced by the Enlightenment ideas.
Some differences between the two revolutions that I found were...
The geographical differences is an obvious difference. Also, France wanted a new government and more money and food supply, and America just wanted their independence from Britian.
America had taxing problems and acts from the British that were hard on them, and France were the ones hard on others for money to refill their supplies.
The countries fought different battles. America had much more military than France in their revolution.
France declared war on other countries, unlike America.