新たと新しいの違いは何ですか。
Both of these mean "new" in English, but is there a difference? For example:

Are both of these sentences okay?
•新しい車を買った
•新たな車を買った

•新しい遊園地が公開されました。
•新たな遊園地が公開されました。

Please explain and write example sentences. It helps me to understand better.

Question

新たと新しいの違いは何ですか。
Both of these mean "new" in English, but is there a difference? For example:

Are both of these sentences okay?
•新しい車を買った
•新たな車を買った

•新しい遊園地が公開されました。
•新たな遊園地が公開されました。

Please explain and write example sentences. It helps me to understand better.

Answer

Maybe you know 新しいis i adjective and 新たな is na adjective.

The difference is we normaly use 新しい in daily conversation.
For example 新しい車ですか？ means Is it a new car?

On the other hand, 新たな is more formal. It is used in speech, news and newspaper.
For example 新たな挑戦が始まりました。means A new challenge has begun.
You can say 新しい挑戦が始まりました。

We sometimes use 新たな in a conversation with our intimate people for joking.

Answer

As a note, 新しい  does not have its corresponding verb while 新た(ARATA) has one.
It is 改める（ARATAMERU). 
As this verb shows, ”新た" has a touch of  "reset, starting over".
It  is the semantical difference from "新しい"