There is a difference
Well there is actually alot of difference in your aim point, but it does depend on your bow and its speed. If your using the same pin to shoot at 40 & 45 yards, then there will be no difference, but if you have 2 different pins for those distances for your bow, then there will be a difference.
And I use this as the example.
If your 20 feet up a tree and you range the target at 45 yards. The actual distance to the target from the tree your in is a tad over 40 yards (40.3 actually). So you should use your 40 yard pin. (arrows care about the distance that gravity effect them). Also you should aim with the trajectory in mind that the arrow will travel thru the targets body with vitals in mind.
There is a general rule of thumb if your using a range finder without angle compensation to just subract 3 yards from the measurement (close ranges... ie bow range) but that of course depends on how high up you are as well.........