In a multi-track recording of an album in its simplest form, it has only the same number of recorded tracks as there are people to play instruments. This means that we're looking at the basics of drums, bass, guitar, keys, vocals, and any other instrumentalists you want to include. Each of these instruments would get its own track in the recording that you can then use to mix together to create an environment around the music that best suits it. This could mean creating an intimate venue for an acoustic performance, or a concert hall for an orchestra.
This is not how many recordings are released, though. Most will have layered vocal tracks providing multiple harmonies, perhaps multiple guitar tracks to create a broader musical arrangement, string pads, or other sampled instruments to create a wider dynamic range. So the question becomes, after going through the process of creating a detailed and intricate mix in the studio, how can you recreate the album on stage?
Most artists, in the internet and social media age, are discovered by the majority of their fan base through a recording, either streamed, downloaded, or shared by a friend, not a live performance anymore. This way of discovering new music has a tendency to create a certain expectation when you hear that band. You go into a show wanting to hear your favorite track performed live, but if the production was too sophisticated and layered that becomes very hard to duplicate. So how do you keep your fans happy while still taking into account that a high quality production will help draw more people to you?
There are 3 ways that I've seen this done well that are generally accepted:
1. Hire more musicians to play the extra parts. Sure, your track may have 3-4 guitar tracks that layer themselves in the recording, so why not hire at least one extra guitar player to help you pull it off and make the live performance a little bigger and more dynamic? This way, of course, generally takes a little extra cash to be able to pay these musicians, which isn't always available.
2. Focus on the simplified version of the song. Namely, lose the layers. John Popper is one of the guiltiest musicians when it comes to plugging in massive amounts of layered vocal tracks. Many times he's not even singing the same lyrics or melodies. So how does he do this live? He picks the main vocal line and sticks with it. Understanding the separation of the recording and live performance and how to do each can be an art in and of itself. So when you're on stage, find a way to keep it simple.
3. Digitize/automate the extra tracks. This can be seen as a way of lip-syncing for musicians and some might look down upon it, but it will allow you to create those multiple layers and would be one of the most accurate ways of duplicating the album as you can use the exact same digital tracks as were used during the recording.
I'm not going to state which of these is better than the others because the fact remains that it is completely dependent on your budget, the type of music you're playing, the venue you're playing, and the engineer you're working with as to what the best solution may be.
I bring this up only as a cautionary point to those young musicians that are planning to put out their early materials. If a young engineer tries to talk you into getting overly complicated in the production, and if your goals are gigs and exposure, then create something that you can repeat as close to the original recordings as possible. You are getting out there early in your career and are using these materials to grow your mind share with the fans. Give them the same experience away from your performance that they can get at one of your shows. This will keep them coming back for more as your career and materials develop and improve. Don't sell your fans a production; sell them who you are as an artist and performer while creating music that demonstrates that and let the fans flock to that.