Let's consider the procedure for obtaining citizenship. First, you must take and fill out the documents for citizenship ( at this stage I applied here https://usimmigrationforms.com/ , it is very difficult from the first time to fill all the documents correctly) , secondly, you must pass fingerprints, in the third you must pass an interview. There you get a book on which you need to prepare before you take the oath. You have a whole month to learn everything from the book and successfully pass the test. After the interview, this is not the worst thing. The whole procedure took me two months. But before that I lived in the country for 5 years on a student visa.
In UK you can take as many tests as you like. You can also take the test as many times as you can in USA but as many times as you would give the test, your chances will be as much lower. Try practicing the test online and visit the following link.
www.us-immigration-attorney.com
www.us-immigration-attorney.com