Both the Americans and British had unique sets of advantages and disadvantages leading up to the American Revolution. In terms of advantages, the British had many. They had more of everything a nation would need in terms of supplies needed to wage war. They had more weapons, gunpowder, uniforms, and the greatest navy in the world at the time. Their soldiers were well trained and confident, and Great Britain's economy was powerful and able to finance all their needs including the payment of mercenaries. Despite everything they had in their favor, the British did have some disadvantages. Primarily, they were fighting a war thousands of miles from home, which provides many tactical issues as well as problems with communication. Many of their officers did not play a role in the French and Indian War and were unprepared for the guerrilla style tactics that the Americans would employ in the conflict. Lastly, their soldiers didn't have the motivation to fight that their opponents held. Of course, they didn't want to die, but they weren't fighting for themselves.
The Americans main disadvantage was a lack of everything the British held in abundance. On several instances Americans were winning battles, but had to abandon the fight because they ran out of ammunition. They lacked supplies, weapons, and the Continental Congress continually failed to provide General Washington with the necessities he was promised. Their soldiers were not well trained and there was no real navy to speak of at the beginning of the war. Despite these disadvantages, the Americans did have some great advantages. They were fighting a defensive war, which is always favorable. They understood the land and didn't have the logistical problem of a three thousand mile supply line. While the Continental Army as a whole was untrained, many officers and soldiers did have experience in the French and Indian War, and the guerrilla battle tactics they learned there were invaluable in defeating the British. Probably most important was the American will to win. They were fighting for their lives, homes, families, businesses, faith, and ideas. Winning wasn't just important, it was essential, and the Americans fought with the zeal of people protecting their existence.