Is there really that big of a difference between basic and advanced obedience?
Short answer yes.
Basic obedience gives a great foundation for a well behaved dog. Through basic obedience you will learn on leash control of dog, socialization, addressing issues as dog matures, teaching dog to focus on handler, intro to commands: heel, sit, down, stay.
Advanced obedience gives you the freedom to trust your dog off leash, have total focus on handler regardless of situation, and know commands: sit, down, stay, heel, come, lay down; with the introduction to a finished heel.
Advanced obedience does come with the maturity of the dog; however, once it is achieved dog and owner will have a knowledge of mutual understanding, communication and respect.