I know this will sound like a rookie question but I have many guitars and I find that the volume on them varies quite a bit, even with the same type pickups. Some of my Gibson hummbuckers are louder on 1 than my other Gibsons on 4.
The single coils are the same some have no volume at all and others blow you away.
I use my amps and pedals on the same setting most of the time so I really notice it changing guitars.
I understand the ohm output ratings and most of the pickups are in the same range other than my ceramic humbuckers.
Is it Pots, caps, or more windings on the pickups? My 1990 Les Paul is amazingly loud.
I have never really researched this topic and most pickup info gives the output and the resistance but doesn't really go into the volume thing.
Just a thought for a Sunday morning.