There are two types of transaction outputs if we apply classification based on their status: unspent transaction outputs (UTXOs) and spent transaction outputs (as far as I know, this type didn't get a well-established acronym, but we can call it "TXOs" for short.) Your wallet shows only UTXOs in the "Coins" tab because it has corresponding private keys to them and manages all information necessary for transaction signing and broadcasting. On the other hand, TXOs have already been used and spent to the addresses to which your current wallet has no private key. It still may show these outputs in the transaction history, but it is mainly for user experience. Please note that not all wallets can show UTXOs as a separate list of selectable items: this feature is known as "Coin control" - a privacy-enhancing technique aimed at giving users more control over addresses and transactions.