The recommendation for this scenario is to define one business unit and two project units. A business unit is an organization that performs one or many business functions such as transaction processing or reporting. A project unit is an organization that manages projects within a business unit or across multiple business units. By defining one business unit and two project units, you can meet the following requirements of the client organization:
The management reporting and transaction processing requirements are the same for both the organizations: This can be achieved by using the same business unit for both the organizations, as the business unit determines the common setups such as ledger, currency, calendar, etc. for transaction processing and reporting.
The project planning, management, analysis and reporting requirements are different for each organization: This can be achieved by using different project units for each organization, as the project unit determines the specific setups such as project types, templates, options, etc. for project planning, management, analysis and reporting. Defining two business units and two project units is not recommended for this scenario, as this would create unnecessary duplication of setups for transaction processing