This is a great question! Gold-filled is much more durable than gold-plated, making it far more valuable. Think of gold-filled as a cozy coat with a lush wool outer layer. Gold-plated would be a coat with a delicate lace outer layer. The lush wool coat will definitely keep you warmer and will last longer. The lace coat will look very pretty for a time, but it will not keep you warm and there's a good chance it may rip.
Gold-filled is a solid layer of real 14k gold securely bonded to a high-quality base metal like jeweler's brass. It's not just a surface coating – it's heat and pressure combined to ensure it stays put. So, it's like enjoying the gold look without breaking the bank!