Predictive maintenance is based on determining the condition of a machine while it is in operation. The concept relies on the idea that machines will give some kind of warning before they fail, and this type of maintenance aims to detect those symptoms in order to take action. 

Preventive maintenance is a scheduled activity that involves inspections—both operational and safety—adjustments, repairs, analysis, cleaning, lubrication, and calibration, which must be carried out periodically based on an established plan. The purpose is to anticipate and correct faults or defects in their early stages to keep the system fully operational at optimal levels and efficiency. Preventive maintenance helps detect recurring failures, reduce downtime, extend equipment lifespan, lower repair costs, identify weak points in the system, among many other benefits. 

Corrective maintenance refers to the maintenance performed to fix defects found in equipment or installations. It involves identifying faults or malfunctions in order to correct or repair them.