A freight forwarder is a firm specializing in the arrangement of cargo on behalf of shippers. In most cases, freight forwarders provide a variety of supply chain services, including: Ocean or air freight transportation.
A carrier is a company or a person legally entitled to transport goods by land, water, and air. Usually, the carrier works with shippers to ship goods from one place to the other.

Freight Forwarder do not own the trucks, ships, or planes but act as middlemen who arrange the transport of goods. They handle documentation, work out the best routes, and negotiate prices. For businesses that send products across borders, freight forwarders deal with customs and other international regulations.
A Carrier, on the other hand, is the company that owns the means of transportation. Be it trucks, ships, or airplanes, carriers are responsible for physically moving the goods. They take responsibility for ensuring goods get from one location to another safely and on time.
Businesses might have a more direct relationship with freight forwarders, discussing their needs and concerns.