They use the same numbering system, as a the workflow as presented earlier, shows that a regular incident becomes promoted to a major incident (and can thus be tracked as a major incident).

A simplified way of thinking about this, is that a major incident is still an incident (much like different priority of incidents are still incidents). One of the main differences around Major Incidents comes down to communication (which also has several handy features available).

More information exists on docs:

https://docs.servicenow.com/bundle/xanadu-it-service-management/page/product/incident-management/con...

And since you're asking specifically about tracking and management, you can find more useful information using the Major Incident Workbench and Major Incident overview.

https://docs.servicenow.com/bundle/xanadu-it-service-management/page/product/incident-management/con...

https://docs.servicenow.com/bundle/xanadu-it-service-management/page/product/incident-management/con...