in future, there may arise 512 L2 cached versions of 4000+ on 90nm fabricated wafers. at eh same time it isnt true to say that 4000+ didt came with 1MB L2 and is on 90nm.
to me they look itentical on the specs. I don't know about the multiplier/fsb cuz I don't have those (wish I did) but I think they will benchmark the same.