Canon's Rebel line has had this "T" series going on for years... T1i, T2i, T3i, T4i, etc. until they got to the T6i when that came out in two editions... the T6i and T6s. The difference between the "i" and "s" was largely that the body on the "s" had control layout a bit more similar to the mid-range cameras (like the 50D, 60D, 70D, 80D) in that they added a top-lcd display and the back got a 2nd control dial (e.g. if you shoot manual then you can adjust shutter speed with the front dial and aperture with the rear dial... it's quicker than how you'd do it on the other Rebels).
When they came out with the T7i, the camera you would think they would call the T7s... was actually called the 77D (I think Canon figured out the whole "i" vs "s" thing was confusing so they wanted to use the mid-range numbering system so people would realize the model is elevated to a slightly higher category.
The T7i / 77D is a noticeable upgrade over the other Rebels. Most new models are the same as the last model with slight improvements. The T7i got lot of improvements... a new sensor with noticeably better performance, a significantly improved auto-focus system vs. the previous Rebels, and it's the first of the Rebel line to get true "Dual Pixel CMOS AF" (phase-detect auto-focus on the sensor ... fantastic for video or live-view shooting).
I own a 60Da ... a special edition of the 60D designed for astrophotography (normal cameras have filters in front of the sensor to limit the percentage of light transmission to match the human eye (we are most sensitive to colors in the middle of the visible spectrum... less sensitive to the edges. In the astrophotography edition, the camera still has a filter to block UV & IR but allows the visible part of the spectrum to pass without blocking. This creates wonky looking images if used for normal photography but fantastic performance for astrophotography (especially nebulas)). I love the camera... but it's the same sensor that the T2i, T3i, T4i, and I think even the T5i had... as well as the 7D (they all had Canon's 18MP sensor) So the 60D would be an upgrade in terms of resolution and ISO performance... but not nearly as much as the T7i or 77D.
One notable missing feature of the 60D is that it does NOT have auto-focus micro-adjustment. This is a feature that ALL mid-range cameras had... EXCEPT the 60D (why Canon left it out of that camera is a bit of a mystery but they took a lot of flack for it.) This feature lets you fine-tune the auto-focus performance on a lens-by-lens basis. No Rebel models had this, but the mid-range and high-end cameras all had it (with the exception of the 60D).
I DO take advantage of the weather-sealing. When you image at night and the temps are dropping and the dew starts falling (and it really starts falling... at the end of the night everything is absolutely soaked)... the camera is fine. I towel it dry and put it away.
It's not waterproof... it's weather resistant. It shouldn't be submerged, but a light rain or splash isn't going to hurt it. But you also have to consider if your LENSES are weather sealed. It doesn't do any good to have a weather sealed body if the lens isn't also weather sealed. No EF-S lenses are weather sealed. But many (possibly most) of Canon's "L" series lenses are weather-sealed. Usually you'll notice a silicone skirt/gasket where the lens mates to the body if it's a weather sealed lens.
The weather sealing is moderate... I don't know that I'd trust it in extreme weather.
You can see a comparison table here, but this table doesn't include the mid-range models such as the 60D, 70D, 80D or 77D.
https://downloads.canon.com/nw/came...ocs/canon-eos-rebel-dslr-comparison-chart.pdf
