Many companies act as both brokers and dealers, and are thus called broker-dealers.
A broker is a person or company that brings together buyers and sellers of securities, such as stocks or bonds.
For example, if the broker’s customer wants to buy stock of a particular company, the broker finds a seller, facilitates the trade, and charges a commission on the transaction.
A dealer, by contrast, directly participates in the transaction.
For example, a dealer may buy shares of stock from the other party for its own accounts, or sell shares it already owns. While brokers make their money off trade commissions, dealers make money on the difference between the money they pay for the security and the money they sell it for.