Similar-sounding middlemen with different responsibilities. Part of freightcalcs.com.
A freight broker arranges transportation: it matches your load with a carrier, takes a margin, and never touches the freight. Legal responsibility for the cargo stays with the carrier. A freight forwarder takes possession: it can consolidate your cargo with others', issues its own bill of lading (a house BOL), and assumes carrier-like responsibility for the shipment, often across multiple modes and borders.
In practice: domestic truckload and LTL usually involves brokers; international ocean and air almost always involves forwarders, because consolidation, customs documentation and multi-leg liability are the whole job. Small importers typically need a forwarder first and a broker only as domestic volumes grow.