The Southern Conventionalist Church is a different sect of pantheon and Gaial-centered worship that originated during the breakup of the True Church of Gaial and The Order during the Order Reformation Acts. While the True Church of Gaial fell apart due to their restrictive policies, a state-backed alternative to the Order's interpretation of the pantheon stuck around longer. The Southern Conventionalist Church doesn't differ much from the Order's interpretation in its core beliefs, I.e in a pantheonic collection of gods with Gaial at the center. However, the differences stem from the schism between the traditionalism of the True Church and the reforms of the order.
While not as hardline as the True Church, the Conventionalists are much more draconian about religious matters than the Order. Marriages and other interpersonal relationships between religious officials and any other people of any kind are strictly forbidden. Rituals within the Order were partially erased for fear of being too monotheistic for the pantheonic structure, while the Conventionalists embraced rituals. While the Order worships the pantheon as a whole, the Conventionalists worship them individually. An example of this would be that a priest of the Order would tend to the shrines of all the gods while a Conventionalist priest would be assigned a god to care for.
This led to an informal caste system within the Conventionalist Church, with the head priest of Gaial considered the head honcho in his little Conventionalist sphere of influence, with all the other priests lagging behind. While in the Order, religious authority coincided with political authority with the theocratic city-state in southern Valdar in the Citadel serving as both the center of the Order faith and a powerful political entity. The Conventionalist Church, on the other hand, was under the command of the Kingdom of Falglor, who had maintained the faith, had it closely intertwined with its political system, causing the Conventionalist Church to be under the purview of the Falglorian state. There is no one central head of faith like the Grandmaster in the Order in the Southern Conventionalist Church, with power decentralized to a pseudo-official council of Gaial priests that still defers to the central political institutions of Falglor.
The Southern Conventionalist Church isn't as widespread as the more established and international Order system of faith, mostly proliferating in the (shocker) south, mostly in places where Falglor has either trade or political influence, like in limited enclaves in Uthan (formerly), Teckitan, The Yunnaiteddo Federation, and the Kingdom of Adhyria, in which the religion was imposed upon them. There is, of course, throughout the entire world a small minority of Conventionalists, either from Falglorian merchants passing through or settling permanently in other regions. These far off regions, disconnected from the wider Conventionalist network centered in Falglor, didn't have the same rigid hierarchy of priests and disdain of nonbelievers while also being exposed to reformist Order ideas. These separated Conventionalists- by no means unilaterally- began to sort of take a more reconciliatory and reformist view of Conventionalism while also separating themselves from the Order faith.