essentially not a huge amount, they are both the same instrument with the same type of action mechanism and tines, but the differences are the year they were built, and some components inside which create a different tone quality. Harold Rhodes’s company collaborated with Fender, which helped manufacture the pianos from the era of 1970 to 1973 (check dates). these pianos have wooden hammer cams and small hammer tips, whereas the more modern ‘rhodes’ pianos from 1975 onwards have plastic hammer cams and angled hammer tips. the difference is the sound which is created, with the earlier pianos arguably having a ‘truer’ sound. the older pianos are generally favoured for this, but as with all vintage instruments, a mentality of ‘the older the better’ also exists here too. personally i prefer the sound of the older ones, but its not a dealbreaker at all. an easy way to distinguish between them is the fender pianos have “Fender Rhodes” this written on the name board in the centre of the piano, whereas the later rhodes model just have “Rhodes” written on.