Actually there's not much difference. Both are thin coverings of gold. The gold in 'gold plated' is a little thinner. 'Gold filled' is done by physically rolling gold to a very thin layer and bonding it to metal with heat. But gold can be rolled VERY thin, much thinner than, say, aluminum foil. Gold plated is gold deposited by a plating bath that the base metal is dipped into. It's deposited one molecule at a time, so it can be very very thin.

Gold-plated jewelry consists of a lower-quality base metal coated with a very thin layer of gold through a chemical process, while gold-filled jewelry has a thicker layer of gold bonded to a base metal through heat and pressure.

They are technically the same thing. People dislike gold plated because the gold wears off quickly so the manufacturers came up with a new name for it "gold filled."

There is more gold with gold filled.