I was just about to suggest this idea, but I think that it should go without saying that it needs more detail to interest the general public. I personally make packs based on my own previous packs and sometimes creating a new mod pack for the same or even different versions should be as simple as pressing the comparison button and open two instances at the same time to view and compare active mods, different mod versions, active resource packs, etc. This would help me tremendously as it can be very difficult to go back and forth between two instances trying to find out what mods I'm missing or need to remove. It's been years of me having to record my screen and compare both mod packs by watching the video while scrolling on the other instance.