The windings were more random and not so cleanly precision wound.
I think there's a nice explanation on the FAQ page:
What is scatterwinding?Scatterwinding is the process of guiding fine copper wire by hand in a random or scattered pattern around a bobbin that is spun by a machine. True scatterwinding can only be done by hand and requires a degree of skill to get the required tension along with consistent results.
Are all scatterwound pickups unique?To a certain extent each pickup will be unique and have it's own character but within the boundaries of its specification. For instance no two Riff Raff humbuckers will be identical but they'll all have the same number of winds, the same wire, the same magnet and therefore similar overall sound characteristics and performance.
Why do scatterwound pickups sound different to machine wound ones?Scatterwinding by hand can be time consuming but it has many advantages over conventional machine winding, not least a far superior sound. When a coil is scatterwound, the wire isn't as close or even, layer on layer, as with a machine and this lowers the distributed capacitance that exists between the turns of the wire. Lower capacitance allows more top end through, the resonant peak increases slightly and the pickup has a flatter frequency response across its range. The result is a clearer, more open sound that has the impression of being louder purely by the amount of extra detail and dynamics present.