An NFT is a non-fongible token built by blockchain technology. They repersent unique, indivisible, and interoperable proofs of digital asset ownership stored on blockchain network.
A FT(Fungible Token) is a native token minted under fungible token standard. It's interchangeable with other FTs, just like you can swap$1 USD with others who have $1. Most digital assets like Bitcoim, Ethereum and stablecoin like USDT are fungible, making them a medium of exchange in crypto world.
Non-Fungible Token, however, is unique and totally different from other NFTs. This characteristic makes NFT a perfect example of a collectible or representation of real world assets.