The two categories are funded differently and justified differently, and confusing them is the most common reason a maintenance budget underperforms.
Preventive maintenance is applied to pavement that is still sound, to slow its decline. Crack sealing and sealcoating are the main examples. Neither adds structural strength, and neither fixes anything that has already failed. What they do is keep water out and slow surface deterioration, which is worth a great deal because water reaching the base is what turns surface problems into structural ones.
Corrective repair addresses pavement that has already failed: patching, dig-outs, full-depth repair, and eventually removal and replacement. It costs substantially more per square foot than preventive work, which is the entire argument for funding prevention on pavement that does not yet appear to need anything.
A realistic program usually runs both at once: corrective repair on the areas that have failed, preventive treatment on the areas that have not. A proposal that offers only sealcoating for a lot with visible base failure is treating the symptom that shows rather than the problem that matters.