Everything else that gets listed as a difference between these two follows from one thing: what causes a job to exist. Preventive maintenance is triggered by an interval elapsing, whether that interval is counted in months, running hours or miles. Predictive maintenance is triggered by a measurement changing on the asset itself. Once that is clear, every other difference people list, the cost, the skills, the equipment, the failure modes each one catches, stops being a list to memorise and becomes a consequence you can derive.
The trigger, and what follows from it
An interval trigger needs nothing but a date or a count and something to remember it, which is why preventive works on any asset immediately. A condition trigger needs a measurement, which needs an instrument, a baseline of what normal looks like, and somebody who can tell a meaningful change from noise. That single requirement is the origin of every cost and skill difference between the two.
What each one is structurally blind to
Preventive cannot see a failure developing between visits, so it either services often enough to catch it or it misses it. Predictive cannot see a failure mode nobody is measuring, which is most of them: monitoring vibration says nothing about a corroding drain pan. Both blindnesses are structural rather than fixable by doing the same thing harder.
Why the choice is per asset and not per site
Because the two inputs vary per asset: what a failure costs, and whether it announces itself. A site is a mixture of assets with different answers, so it is a mixture of strategies. Adopting one wholesale means over-serving the cheap assets or under-watching the expensive ones, and usually both at the same time.
Questions people ask about difference between predictive and preventive maintenance
Is predictive maintenance more advanced?
It is more instrumented, which is not the same thing. A well-run interval programme on the right assets beats a monitoring installation nobody acts on, and that comparison happens more often than the marketing suggests.
Which one costs less?
Preventive costs less to start and more per asset over time in visits; predictive costs more to start and less in unnecessary visits on the assets it covers. Which wins depends entirely on what a failure costs you.
Can an interval be based on a condition reading?
That is essentially what a hybrid programme does: the reading moves the due point while the interval remains a backstop. It is a good arrangement and it needs both systems talking to one record.