Gold-fill is 50 to 100 times thicker than regular gold plating, and it is about 17 to 25 times thicker than heavy gold electroplate. The base metal used is usually brass, copper or steel. Gold-filled items are made by combining a layer, or layers of gold alloy to a base metal (usually brass) then rolling or drawing the metal to the desired thickness and shape.
Gold-plate is a very thin deposit of gold, electroplated or electrochemically applied to the piece. The industry standard is 0.15 to 0.25 mils thickness of gold-plating to the surface of the base metal; it is a very small fraction of an inch thickness (1/1000 inch to 1/1,000,000 or so). Heavy gold electroplate might be 0.002 or 0.003 inches thick. Gilt is another term used, which means there is a very thin finish of gold color over the base metal which may or may not actually be gold.