One supplies water to the shower; the other removes used water. Their purpose, connections and fault observations are different.
What the observation means
A noisy unit near the bathroom is not enough to identify which type it is. Existing labels and installation paperwork are safer references than tracing hidden pipes.
A useful next step
Explain whether the problem is weak water delivery or slow drainage. If uncertain, say so and provide accessible identifiers. Do not open the equipment or apply macerator cleaning products to a clean-water pressure pump.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.