The '51-style single coil is quite a bit more percussive. The split coil P is a bit softer on the attack. As chef has said, the reisssue pickup on the Fender is pretty hot.
Also, the '51 single coil is a smidgin closer to the neck than the split coil or neck J pickup is, so the sound is a tiny bit darker, at least to my ears.
Also, the '51 single coil is a smidgin closer to the neck than the split coil or neck J pickup is, so the sound is a tiny bit darker, at least to my ears.