以上術(shù)語被不少詞典都譯為“定金”，但實際上它們之間是有較大差異的。其中，deposit (也稱為security deposit)是“履約保證金”，擔(dān)保合同的履行，如違約，則將喪失此筆保證金[1];合同一方收到deposit后，一般不能先動用；deposit也可作為押金，如圖書館借書所交納的押金，如不歸還所借之書， 押金則會被沒收；其也可等同購物前所交納的“定金”[2]。earnest (也稱為 earnest money; bargain money; caution money；hand money)多指在買賣中的“購貨定金”，起源于動產(chǎn)買賣，其現(xiàn)在常用于不動產(chǎn)交易，且經(jīng)常交由第三人代管（in escrow)，如違約不買，也會被沒收[3]。down payment多指締結(jié)合同時約定付款中的“首付款”或“頭款”[4]，其與deposit有區(qū)別的是合同一方收到down payment后，即可動用；且down payment不具有定金所含的如果違約則應(yīng)雙倍償還的性質(zhì)。

[1]“ Money placed with a person as earnest money or security for the performance of a contract. The money will be forfeited if the depositor fails to perform." Cf. Bryan A. Garner, Black's Law Dictionary, 7th edition, at p. 451，West Group (1999).
[2]“ Money given in advance so that the thing which you want to buy will not be sold to
someone else. ”Cf. P. H. Collin, Dictionary of Law，2nd edition, at p. 164，Peter Collin
Publishing Ltd. (1993 ).
[3]“A deposit paid (usu. in escrow) by a prospective buyer (esp. of real estate) to show a good-faith intention to complete the transaction，and ordinarily forfeited if the buyer defaults. ” Cf. Bryan A. Gamer, Black's Law Dictionary, 7th edition, at pp. 525 ?526， West Group (1999).
[4] "The portion of a purchase price paid in cash (or its equivalent) at the time the sale agreement is executed. Id. at p. 1150. "A some of money, the value of a negotiable instrument payable on demand, or the agreed value of goods，given on account at the time of the contract. ”Cf. Daphne A. Dukelow, The Dictionary of Canadian Law, at p. 304, Thomson Professional Publishing Canada (1991).