以上术语被不少词典都译为“定金”，但实际上它们之间是有较大差异的。其中，deposit (也称为security deposit)是“履约保证金”，担保合同的履行，如违约，则将丧失此笔保证金[1];合同一方收到deposit后，一般不能先动用；deposit也可作为押金，如图书馆借书所交纳的押金，如不归还所借之书， 押金则会被没收；其也可等同购物前所交纳的“定金”[2]。earnest (也称为 earnest money; bargain money; caution money；hand money)多指在买卖中的“购货定金”，起源于动产买卖，其现在常用于不动产交易，且经常交由第三人代管（in escrow)，如违约不买，也会被没收[3]。down payment多指缔结合同时约定付款中的“首付款”或“头款”[4]，其与deposit有区别的是合同一方收到down payment后，即可动用；且down payment不具有定金所含的如果违约则应双倍偿还的性质。

[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).