Okay, so you know the main difference between the two: Major Arcana has 22 cards and Minor Arcana takes up the other 56 cards. Sweet. But what are each for? Why does the tarot deck have to be split into two separate sections anyway??
The best way to answer this is by differentiating their functions. The 22 cards of the Major Arcana are meant to represent a "hero's journey"—starting with the naive fool and ending with the karmic World. On the flip side, the Minor Arcana then represents smaller trials and tribulations that the hero faces along the way.
Tarot's Major Arcana
These cards make up the 22-card Major Arcana:
The High Priestess
Wheel of Fortune
The Hanged Man
It may come as a surprise to you that the arc of the Major Arcana is meant to represent the arc of human life: from birth to death. It may then come even more as a surprise to you that this is similar to astrology's birth chart wheel: From I House (Aries) to XII House (Pisces), the birth chart wheel is meant to chart out human life. When you take each zodiac sign's Major Arcana card into account, this all really starts to make sense—as we piece together the Major Arcana to represent the "hero's journey."
If you think about "life" as a concept, we start out as babies—totally unaware, totally free, blissfully ignorant of our situations. It's no wonder then why the Major Arcana starts with naive, cards such as: The Fool (conception), The Magician (preparation/tools for the world), The High Priestess (beginning of consciousness), and The Empress/The Emperor (identity).
As we move into the second phase of our lives—adolescence—we encounter new Major Arcana cards that give us meaning: The Hierophant (a teacher/religion), The Lovers (first love), The Chariot (feelings are power), and Strength (sense of self and re-established identity).
We then move into early adulthood, where we encounter some real curveballs: The Hermit (self-improvement), Wheel of Fortune (good or bad luck), Justice (a tough decision), The Hanged Man (our personal demons urging to be resolved), Death ("letting go"), Temperance (higher learning), The Devil (a toxic relationship with someone or something), The Tower (learning a karmic lesson).
Finally, we enter the last phase of our adulthood: enlightenment. That's where we see more ethereal cards such as: The Star (inspiration), The Moon (intuition/creativity), The Sun (strength), Judgment (forgiveness), and The World (karmic wholeness).
Tarot's Minor Arcana
Whilst both the Major and Minor Arcana discuss portions of the hero's spiritual journey, the Major Arcana represents “major” moments of our spiritual evolution (not just personally, but within a job, a relationship, etc.), whereas the Minor Arcana symbolizes in-the-moment character traits, flaws, and feelings.
The Minor Arcana's 56 cards can be best described as character traits. They are the fleeting parts of humanity that we work with on a daily basis. For example, Three of Swords? Betrayal. Ace of Cups? New relationship or friendship. Five of Cups? Sadness. Two of Cups? True love. All these cards are important, but they also have little to no spiritual value—because they are simply the feelings you have or the situations you're placed in that will help guide you to the next spiritual chapter.
It's obvious then that the Major and Minor need one another to complete the whole "hero journey." If anything, I'll leave you with this metaphor: If the tarot deck were a book, the Major Arcana would be the story arc or plot, and the Minor Arcana would be the specific traits or experiences that develop the character along the way.
P.S. If this interests you, I'll be including this and SO MUCH MORE in my upcoming tarot masterclass series—coming to soon!