Since your second point referenced penetration, I ran it thru my calculator that accounts for bow weight, arrow weight, wind speed, speed of the earth spinning on it's axis, temperature, humidity and relation to the moon and it shows the heavier arrow, after going thru the deer, will penetrate the ground .001379 inches more than the lighter arrow. Now you know based on scientific evidence and a complex algorithm.
Seriously though, I don't think you can tell a difference and you said they were both shooting well, so go kill something.