I think all that can really be said is that a googolplex is much, much smaller.

This isn't a direct comparison of a googolplex with Graham's number, but maybe it will help give some perspective:

Some back-of-the-envelope/Mathematica calculations tell me that

$10^{(10^{100})}\approx 3^{(3^{(3^{4.86})})}$

and so a googolplex is between $3\uparrow\uparrow 4=3^{(3^{(3^{3})})}$ and $3\uparrow\uparrow 5=3^{(3^{(3^{27})})}$ (much closer to $3\uparrow\uparrow 4$, obviously).

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I think all that can be said is that a googolplex is much, much smaller.