TBH there really isnt much difference sonically, maybe the MIJ has a bit more treble bite and '71 more woody lows but its marginal. The MIJ is slab whereas the '71 has a belly cutout (which I sadly need!) - the latter is lighter by 1 pound, probably due mainly to this.
Both are great basses but I love the mojo, weight and vintageness (its a word) of the '71 more