这些单词均有“中间人”或“居间人”的含义，但各自有一些差异。其中，broker为“经纪人”，主要是指以收取佣金 (commission)为目的而代表他人直接参加谈判，议价，进行买卖交易者，故其更接近买卖代理人的含义，其可参与多种交易， 如不动产买卖、证券、股票交易等[1] 。intermediary为“居间人”或“调停人”，主要是指在分歧双方或谈判双方之间进行斡旋，起联系或谈判作用者[2]。jobber主要是指商品买卖交易中的中间人[3]。finder则是指为他人寻找商机或介绍客户且因此而领取佣金者，但他却不直接参与交易谈判或运作[4]。middleman所包括的含义较广，其可指仅将当事人撮合一块让他们自己签约者，也可具有broker, jobber或intermediary等的含义[5]。
 
[1]“ A person or entity that puts together a buyer and seller of property or services，acting as an agent for one or both of the parties and taking a commission on the transaction. Examples include a broker who arranges insurance coverage for people or companies，a broker who arranges sales of real property，and a broker who arranges purchases and sales of stocks and bond. ”Cf. James E. Clapp, Random House Websters Dictionary of the Law, at p. 64， Random House, New York (2000).
[2]“ A mediator or go-between； a third party negotiator. ”Cf. Bryan A. Gamer, Black's Law Dictionary, 7th edition, at p. 820, West Group (1999).
[3]“ Someone who buys and sells goods wholesale and handles goods on commission. ” Cf. G. H. L. Fridman，Sales of Goods in Canada, 3rd edition, at p. 493, Toronto, Carswell (1986).
[4] "An intermediary who contracts to find, introduce and bring together parties to a business opportunity，leaving ultimate negotiations and consummation of business transaction to the principals. ” The Publisher's Editorial Staff, Black's Law Dictionary, abridged 6th edition, at p. 437, West Publishing Co. (1991 ).
[5] "An agent between two parties；an intermediary who performs the office of a broker or factor between a seller and buyer, producer and consumer, land-owner and tenant, etc." Id. at p. 685.