Well, let's see.... compared to 70D the 80D has:
1. 20% higher resolution (24MP vs 20MP)
2. 1.5 stop greater dynamic range, higher color bit depth (according to DXO)
3. Higher settable and
usable ISO (according to DXO).
4. 100% viewfinder (vs 98% in 70D).
5. 45-point AF system (vs 19-point).
6. f/8 capable AF system (vs f/5.6 limited).
7. -3EV capable AF (vs -0.5EV or -1EV, depending upon who you believe).
8. Face detection in Live View/video.
... and more. See:
https://cameradecision.com/compare/Canon-EOS-70D-vs-Canon-EOS-80DNote: While helpful and useful, I don't believe everything on that comparison website. For example, I'm pretty sure both 80D & 70D have the same shutter durability rating. It may be 150K, but at least 100K. Another example where I know that site is wrong is it states 80D is "f/8 capable" at only the center AF point. In fact 80D has f/8 capability at up to 27 of it's 45 AF points, depending upon the lens & teleconverter being used. "f/8 capability" simply means more lens/teleconverter combos are able to autofocus on the camera. For example, the Canon EF 100-400mm can AF with a 1.4X on the 80D, but not on a 70D. The 70D is "f/5.6 limited". Generally speaking, "f/8 capability" goes hand-in-hand with lower light focusing capabilities, which the 80D also offers... It's able to autofocus to -3EV, which is approx. "moonlight". That's at least two stops lower light than the 70D... maybe 2.5 stops (the specs for the 70D's AF system differ, depending upon where you look).
Canon USA apparently has a LOT of 80D w/18-55 & 55-250 on hand... So they are blowing them out at bargain prices, before the 90D hits the shelves.
If you don't need the lenses, already have something similar in your kit, you could turn around and sell them. I bet you could get at least $200 or $300 for those lenses... maybe more. That would bring your net cost for the camera down to $500 or $400 and that's truly a bargain for an 80D. (EF-S 18-55mm STM refurb sells for $200, EF-S 55-250mm STM refurb sells for $240. New those lenses sell for $249 and $299, respectively.)