The main difference between fungible tokens and non-fungible tokens (NFTs) is that fungible tokens are interchangeable and identical, like cryptocurrencies that can be traded on a one-to-one basis. In contrast, NFTs are unique and represent specific items, such as artwork or collectibles, making each one irreplaceable and not directly exchangeable. NFTs utilize blockchain technology to establish ownership and authenticity, transforming the way we trade and perceive digital assets.