Substantive examination refers to the National Patent Office’s examination of the novelty, creativity, practicality and other substantive contents of the invention applied for patent. During this period, you may also receive a notice of examination opinion from the Patent Office. Corrections and modifications, etc. In the end, if there is no problem in these three aspects, you can get the patent certificate.
So whether it is difficult or not depends on your patent, but generally speaking, it is more difficult to obtain an invention patent than a utility model patent.