A crypto exchange provides a platform for individual buyers and sellers to trade crypto -- or exchange tokens and fiat currency, like US dollars. Exchange rates are ostensibly based on market prices.
Similarly, a crypto brokerage serves as an intermediary for buyers and sellers, but the broker sets the prices. Brokerages often support fewer cryptocurrencies yet charge lower fees than exchanges. Robinhood, for example, supports only seven cryptocurrencies -- bitcoin, ethereum, dogecoin, litecoin, ethereum classic, bitcoin cash and bitcoin SV -- but charges no transaction fees.