Red Dead Online doesn't play all too differently from Red Dead Redemption 2, but many of the main game's mechanics have been tweaked so that they work more suitably in an online, multiplayer environment.
The most obvious change concerns the Dead Eye mechanic, which doesn't slow time as it does in the single-player campaign. In addition to that though, there are many other subtle changes that may throw first-time players off.
Among the mechanics that have been changed considerably in Red Dead Online is the Wanted System. In the single-player campaign, Arthur Morgan amasses a Bounty depending on the crimes that he has committed and that have been reported or witnessed by lawmen. If the bounty is low, Arthur's life is not in danger, but if it increases considerably, the law will not spare any effort to bring you in, dead or alive. No matter how high the bounty becomes, however, players can pay off the Bounty to get the law off them. Or, they can just ignore it and have to deal not only with the law but also with dangerous Bounty Hunters.
The Wanted System is Red Dead Online works in a significantly different way. In the online multiplayer mode, players don't amass a bounty for their crimes and there are no locked down regions. The game will still display a red circle indicating where the player is wanted, but unlike the single-player campaign,every area becomes dangerous if you're wanted, as the law will follow you pretty much everywhere.
There is also no chance of being brought in alive, as lawmen will always try to kill you.
In addition, things can escalate more quickly in Red Dead Online. If you commit a crime while being chased by the law, stronger lawmen will start coming after you. Plus, if you have any Wanted Criminal in your Posse, you may also become wanted yourself. Riding in a wagon with a wanted criminal will also result in you getting wanted, so be careful who you associate with.
The Red Dead Online Honor System doesn't work too differently from the single-player campaign. The characters Honor Rating will change depending on the actions that are performed in the world. Committing crimes, killing civilians for no reason, ignoring pleas for help, killing and stealing other players' horses affect the rating negatively, while taking care of your horse and helping strangers affect it positively, just like in the single-player campaign.
In Red Dead Online, your honor rating can also improved by reviving dead Posse members, so being loyal to your companions helps in more ways than one.
The big difference, however, is that your character's Honor Rating influences not only how NPCs react to you, but also the available missions. If you're a terrible outlaw, the additional missions available will generally involve getting a criminal out of jail or committing some other type of crime (i.e. doing bad stuff). On the other hand, if you're honorable, your story missions will be radically different and might involve escorting NPCs, defending objectives from other players and so on. You don't get to play both sets of missions.
Since some content may not be available to you due to how the Honor System works, Red Dead Online has a quick way to reset your current rating. Head over to New Austin in the southern part of the map, and access the Old Man Jones' Honor Shop, located very close to the "S" in Austin on the map. Thanks to this shop, you are able to make your Honor rating neutral again in exchange for three Gold Bars. As they are difficult to find at the moment, however, we suggest you do this only when absolutely necessary.
If you don't want to shell out three gold bars for this, there are other - albeit more time consuming - methods available. If you have high honor but want to become dishonorable, you have an easy job. Just kill everyone you meet!
Becoming honorable when you are dishonorable is more difficult. When completing gang hideouts, you should spare the leader. Replay story missions and make honorable choices when given the opportunity. Finally, you can also try hunting down dishonorable posses.