They describe different aspects of the job. A system's ability to move wastewater depends on the complete arrangement, not one headline number.
What the observation means
Pipe route, fittings and simultaneous inflow can affect what is practical. A maximum figure is not a universal installation recommendation.
A useful next step
Have the existing route assessed against the exact manufacturer's guidance where suitability is in doubt. Do not alter pipe sizes, add a vertical section or connect more fixtures based only on a published maximum lift. Repair and redesign are separate scopes.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.