Ever since Red Dead Redemption 2 was announced, and announced to come with an Online mode no less, players have been drawing comparisons with GTA Online regarding mechanics and features. On the one hand, this is to be expected, seeing as GTA 5 is Rockstar's most recent major release, and it's clear that RDR2 will be taking a few pointers from its insanely popular predecessor.

On the other hand, we need to keep in mind that 5 years have passed since GTA 5 was announced, meaning approximately 6-7 years since it entered development. With Red Dead Redemption 2 having been officially announced late last year, chances are it has been in development for 2-3 years already. That means there is an approximate 4-year difference between the start of development on the two games.
Now, in the rapidly changing and evolving AAA development industry, 4 years is a damn long time. Chances are that while there will be a number of conceptual similarities and features that RDR 2 inherits from GTA 5, it will play and feel differently. It's not like there isn't precedent for this, as the original Red Dead Redemption was essentially 'Grand Theft Horse' in terms of gameplay anyway.
We ourselves have done our fair share of connect-the-dots with Red Dead Redemption 2 and GTA 5, including a piece about features the former should steal from the latter, as well as another about the opposite.However, there is one particular core feature that we feel deserves its own mention: shooting.
Shooting is something you do a lot of in Red Dead Redemption, and presumably will in the sequel as well (lacking, of course, any magic or superpowers to dispense of those meddling lawmen and outlaws). Punching just isn't as effective in sandbox games as it is in your average fighting game.
GTA 5 is also as game with lots of shooting. While Rockstar paid attention to filling GTA 5 with various little open-world tidbits that technically don't require violence, there is very little you can do in the multiplayer component, GTA Online, that does not require shooting. Granted, this is partially caused by other players treating the firing of bullets as the only available social interaction, but we digress.
Thing is, 2010's Red Dead Redemption did shooting much better than GTA 5 does. Modern weapons have advanced in complexity and power compared to the Wild West era. Heavy-duty weaponry can send high-calibre rounds through thick armor plating, and do it full-auto, whereas your typical 1900's revolver-round bounced right off anything thicker than a plank.
And yet, Red Dead Redemption's guns feel like they have power, like their shots carry actual force. In GTA 5, it's like you're playing laser-tag, except the lasers cause heart attacks. Instead of feeling like you just sent a high-velocity slug of metal into the body of your enemy, it feels like you're pressing a button which causes their health-bar to get smaller. Even the heavier guns feel like glorified pea-shooters.
Another issue is diversification. In GTA 5, pretty much every gun in a category feels the same. The various assault rifles don't feel distinct and have no character of their own. Sure, there are a few outliers such as the marksman pistol being entirely unmistakable, however the majority of guns feel far too similar. Red Dead Redemption excelled in this regard as well, with each weapon being distinct in its feel and dynamic.
This might also be related to the setting of the games. Relatively speaking, comparing the situation to human history, getting shot these days isn't as big a deal as it used to be. With medical science being what it is, few shots that don't kill instantly will do so later on. Most gunshot wounds can be treated and recovered from entirely. Body-armor also decreases the 'weight' of being shot, and this is felt in GTA 5.
In the 1900's however, getting shot was almost guaranteed to kill you. Medicine was extremely rudimentary and there was no effective form of body-armor available. If you got shot in the leg, something that isn't directly lethal, you'd either bleed out or die of infection. Fun! Whether a conscious decision or not, this might be a cause of Red Dead Redemption placing emphasis on the power of firearms, while in GTA they're just kind of there.
Are you hoping to see improved shooting mechanics in Red Dead Redemption 2?