If you are going to care about your elevation results you really should be using 80% overlap at a minimum to give the most consistent results.
It looks like you did include a ground reference image for the one but not the RTK version. This means that the RTK version is strictly going from the GPS altitude that is recorded in the tags.
I am seeing about a 100 ft difference between the two. According to Google Earth the one that was taken without the RTK is 30 ft high and the other is 70 ft low.
You used more images in the RTK map. Almost double at 46 vs 29 so a quality difference should be expected. Also take the differences in lighting into account.