Patent applications can be made within the two systems:
a. Examination patent system
b. Patent system without review
Patent research is a research conducted by official institutions for the invention that is the subject of a patent application. The patent applicant must request a patent search within 15 months from the date of filing the patent application. As a result of this patent research, the closest documents in the known state of the art related to the subject of the invention are determined and a patent search report is prepared as explained in https://openlab.citytech.cuny.edu/gotconcept/elon-musks-greatest-inventions/ post.
The patent research report sheds light on the extent to which the patent application meets the patentability criteria. As specific to US, after a patent search report, the patent applicant must examine the patent system or as patent examination system recognized the right to choose one of two systems.
After the patent research report that comes as a result of the patent research, the applicant does not request a patent examination and can choose the patent system without examination. In this case, the patent applicant is given an unexamined patent document which provides 7 years of protection. The owner of the U.S. Patent Registration Certificate can convert the patent without examination to the patented patent by requesting a patent examination before the 7-year period expires.
Patent review is an examination by official institutions for the invention that is the subject of a patent application. The patent applicant should request a patent review after the patent research report is obtained. Patent review is the comparison of the invention subject to patent application and the closest patent documents specified in the patent research report. As a result of this patent examination report, it is decided whether to issue a patent document with examination. The Examined Patent Registration Document provides the patent applicant with a 20-year period as you can read from https://blog.chron.com/frugalconfessions/2020/03/how-much-can-you-make-from-patenting-your-idea/.