The main story of Red Dead Redemption 2 takes place in 1899, while the epilogue is set in 1907. This means that there is an 8-year time difference between the main story and the epilogue.
Players have the option to play through the Epilogue separately from the main story, and the setting is quite a different experience. Players will notice the characters have developed somewhat, and there are a lot more opportunities for exploration and side activities.
In the epilogue, players will notice different population and crime levels around the world, as well as advancements in technology, especially in the transportation domain. This means that players will be able to traverse the world of Red Dead Redemption 2 in different ways from the main story, such as using trains and stage coaches.
In conclusion, there is an 8-year time difference between the main story and epilogue of Red Dead Redemption 2. Players will notice a lot of changes between the two time periods, including new transportation options and a developed world.
