Newcomers to the crypto market often confuse wallets with exchanges, but they serve very different purposes. The primary use of wallets is to store your assets, and the primary use of exchange is to buy sell and trade. If you use self custody wallets, you get more security but most exchanges are custodial and you are depended on the platform you are using. You can control your wallet but not the centralized exchanges. Wallets are basically used for long term holding or sending and receiving crypto, exchanges are for trading and exchanging.