「down payment」は頭金という意味になります。ローンで何かを買いたい時に、「down payment」をよく払わないと行けません。これは保証金を意味する「deposit」と違いますね。
What is the down payment for this car?
この車の頭金はいくらですか？
The down payment on this house is 20000 dollars.
この家の頭金は20000ドルです。
down payment の後に、通常「for」か「on」という前置詞を使えます。
◆ deposit （ noun ) ◆
★ A Non-Refundable Deposit
( i.e. As the first part of a larger payment )
[usually singular] ＝（ a deposit )(＋on )
(British English)
・ We’ve 【 put down a 5% deposit on 】 the
house.
・【 The down payment on 】this house is 20000 dollars.
（この家の頭金は20000ドルです。）
||
Ｖ
＜ To put down a deposit on ~ ＞
||
＜ The down payment on ~ ＞
・You can use both
WITH ‘ a deposit on ‘
and WITHOUT ‘ a deposit on ‘
for ＜ A Non-Refundable Deposit ＞
★ A Refundable Deposit
(i.e When they rent something / It is returned to them when you return it you have rented )
[usually singular] ＝(＋pay)（ a deposit )
・to pay a deposit and the annual rent
・a $200 refundable/returnable deposit to rent it
◆ deposit （ noun ) & ( verb ) ◆
★ money that is paid into a bank account
(i.e. Usually,Bank Notes paid into one’s A/C as CR for savings )
・ Deposits can be made at any branch.（ noun )
・I deposit in my bank account.( verb )
＜ ２ways for deposits ＞
・ The deposit ( by cash or by checks )
Let me correct a part of the last comment
below.
★ A Refundable Deposit
(i.e. When they rent something / It is returned to them when you return it you have rented )
↓
(i.e. When they rent something / It is returned to them when they return it they have rented )