They've really tidied the place up a bit in the last 100 years or so, haven't they? Not for the better, as far as I can tell. The original Prestwick looks raw, wild, unkempt and full of bad lies and lousy breaks. The new Prestwick looks like a contemporary golf course with some weird ideas.
My main impression (and perhaps this is a function of the quality of the photographs) is that Prestwick must have rated quite high on the old "resistance to scoring" scale in its day. Look at the green in the first picture; more to the point, where is it? In the updated photo, you can see that the green has a slope from back to front, but it at least looks like a receptive target. I'm not sure what there was to aim at in the earlier photo, or if that rise behind the players was part of the green or just a grassy bank.
In any event, I'd love to play either version, but the old one is the one that fascinates me.