I don't agree that these cameras are different only in resolution for $1400 or that they are both an R6 with only one major feature difference (resolution). I would agree the $1400 might be slightly much for all that you do get, but it is not just resolution on the list.
Just talking resolution, when it is needed, 45 vs. 20 MP allows over a third of the frame to be cropped in either dimension and have the same quality, or it can be down sampled uncropped to eliminate noise. It also allows for larger prints, and I did see my large print quality improve when I went from 20-30MP as it obviously should. I could never go back to my 6D @ 20 MP for many types of shooting I do (timelapse, astro photography, severe weather, landscape) without a significant loss in quality and post processing options. For some people, 20MP might be fine as it was for me for many years, but I push right to the edge of even the 5D4 capabilities currently at 30MP, and that extra 1/4 of cropping I can do is used all the time. 45MP will be even better.
If you consider all the difference between these cameras, the $1400 starts to make more sense and they appear very similarly priced and spec'd to the mirrorless updated equivalents of the 5D4 and 6D:
- 8K (debatable how many of us will actually use it)
- 4K DCI vs UHD (essential if that is your project format)
- +25 MP (significant for many types of photo and video work, and if you need it, you need it.)
- Better weather sealing
- Better LPF
- Higher resolution viewfinder
- Larger rear screen (slightly) with higher resolution
- Faster Wifi and newer bluetooth.
- For 4K video the R5 is full frame vs. a slight crop on the R6 (not a big deal).
- Top screen (RF control ring might make this less needed but still nice to have)
- Several more video modes such as shutter and aperture priority
- More resolutions and codecs
- 3 pin remote shutter release port vs 2.5mm
- Nearly all metal vs part plastic body
- Dual pixel raw (it isn't that amazing in the past, but some new features and DSP are promising)
- R5 ships earlier
For myself, its a bit much and obviously marketing separation, but when considering my needs the 1400 seems worth it in the end and it is hard to regard these as simply two R6 with one having more resolution. I shoot in bad weather, I push resolution, and the better EVF and screen will be welcome for someone used to non articulating DSLR (5D4 and 6D).