The criteria for determining major and minor merits do not have a unified standard, and everything is primarily based on the rewards from alliance tasks.
The difficulty of alliance tasks varies, and so do the rewards, but most tasks reward alliance Contribution Points.
The purpose of Contribution Points is to exchange for treasures below Earth Tier, cultivation techniques, and soul skills in the treasury.
There aren't many tasks that reward minor merits; they only appear occasionally, and are not easy.
Minor merits can be exchanged for treasures below Celestial Tier.
As for major merits, they're harder to obtain. It's not because there are few tasks for major merits, but because the tasks are too difficult, possibly taking years or even decades for someone to complete one.
Of course, items that can be exchanged for major merits are all Celestial Tier.
