Hello, you can check this table that as per v18 sums up what is possible / not possible in each app, and can maybe help you to make a decision on which one to use:

Hello, you can check this table that as per v18 sums up what is possible / not possible in each app, and can maybe help you to make a decision on which one to use:

Each app is designed for a specific use case:
So, the choice depends on who owns the product and where the work happens.
Start with this:
Maintenance - your product, your location
Repairs - customer product, your location
Field Services - customer product, customer location
Also look at your need to use Sales Orders, Subscription Services, Tasks, Timesheets and Worksheets to understand if you are the exception to this "rule".
Odoo's Maintenance, Repairs, and Field Services apps serve distinct purposes despite their similarities.
Use the Maintenance app for managing internal equipment maintenance schedules and preventive tasks.
Opt for the Repairs app when handling product repairs, especially those involving warranty or customer service.
Choose the Field Services app for managing on-site services, such as installations or customer visits.
If you’d like to explore this further for your use case, you’re welcome to connect with us at Pragmatic Techsoft.