Macro photography is all about the skill of the photographer, lenses, and lighting - in that order.

Only after the former have been considered should the differences between two APS-C cameras from the same manufacturer that appear to both use the same sensor be considered as a relatively minor difference.

The primary differences between the EOS Rebel T7i/800D and the EOS 80D are:

• The 80D has an additional control wheel on the back that allows faster handling, particularly in Manual exposure mode.
• The 80D allows AFMA (Autofocus Micro Adjustment), the Rebel T7i/800D does not.
• The 80D has a minimum exposure time of 1/8000 second, the Rebel T7i/700D has a minimum exposure time of 1/4000 second.
• The 80D has a larger viewfinder with 100% coverage and 0.95X magnification, compared to the Rebel T7i/800D's 95% coverage with only 0.82X magnification. In other words the 80D viewfinder will appear to be about 16% larger (21.375 x 14.155 mm) while showing the camera's full field of view, compared to the smaller viewfinder of the Rebel T7i/800D (18.45 x 12.29 mm) that only shows 95% of the camera's FoV. The 80D's viewfinder also has a brighter pentaprism vs the dimmer pentamirror of the Rebel T7i/800D and 3mm longer eye relief (22mm vs. 19mm).
• The 80D can shoot at 7 fps in burst mode, the Rebel T7i/800D maxes out at 6 fps.
• Both cameras have built-in Wi-Fi with NFC, only the Rebel T7i/800D also has Bluetooth.
• The 80D uses the 1865 mAh LP-E6N battery (shared by most of Canon's xD series cameras other than the 1D series) and has a higher battery rating than the Rebel T7i/800D that uses the 1040 mAh LP-E17 battery.
• The 80D has a shutter durability rating of 100,000 actuations. The Rebel T7i/800D does not have a published shutter durability rating.

None of these differences are directly applicable to shooting Macro photography in any significant way.

• Macro photography tends to be done very methodically, so the extra control wheel doesn't really make much of a difference.
• Most macro photography is done from a tripod using careful manual focus or Dual Pixel CMOS AF in Live View, so the lack of AFMA when doing PDAF via the viewfinder is a moot point. Much Macro photography is done using the lens' MFD (minimum focus distance) and then adjusting the camera to subject distance via a macro rail to bring the subject into focus.
• Macro photography usually struggles with having enough light, so the lack of 1/8000 second shutter time is not an issue.
• The differences between the viewfinders is not a consideration if you plan to use Live View, as many macro photographers do, since both cameras have the same rear LCD screen.
• Burst mode doesn't usually apply to macro photography unless one is photographing skittish insects or other moving subjects.
• Bluetooth (or lack thereof), battery life, and shutter durability ratings are not direct considerations for macro photography, but may be considerations for the total value of a camera to a buyer.

For doing Macro photography the way it is practiced by those who do the best Macro work, there's no real difference between the Canon EOS 80D and the Canon EOS Rebel T7i/800D.