Both of the certifications CISM and CISSP are from Information Security domain and are considered elite premium certifications which require aspirants to have experience and knowledge and worked in a similar environment.

Let us figure out the eligibility they both need one by one:

For CISSP prerequisites: There is strict eligibility of 5 years cumulative paid work experience in two or more of the eight domains of the CISSP CBK to appear for CISSP exam certification.
Besides, Isc2 clearly have mentioned a requirement of earning a 4-year college degree or regional; equivalent or an additional credential from the (ISC)² approved list will satisfy one year of the required experience.

As for CISM prerequisites: In order to appear for the CISM certification exam, you must require a minimum of 5 years of work exp. in Information Security domain and 3 among which must be from the listed ones. And all the experience must be within the last 10 years period.

Since both of them require the same kind of eligibility and hold the same recognition in the industry. The difference is in modules and vendor. So, both these certifications need strategic planning to study and maintain a proper plan to pass the exam. So, both these credentials require a study plan and implementation with the latest modules. In our organization, we usually recommend out expert professionals to go for exam preparation from Mercury Solutions. They are one of the recognized training providers who give you options for training in flexible modes, such as classroom in your city or Live Online interactive classes. Also, you get Reference material, Hands-on practice sessions, Mock tests, Live Simulators and more. The best way is to seek their free guidance, call and talk to their training consultants.

Whichever you choose, go for the training program, it is worth every bit of your effort. All the best!

CISM Certification:- https://www.mercurysolutions.co/isaca/cism-certified-information-security-manager-certification-training

CISSP Certification:- https://www.mercurysolutions.co/isc2/cissp-certified-information-systems-security-professional