Let me start by what isn't a split.

Contrary to the west, there isn't the typical left-right split. Frankly, the two competing, mainstream currents are both right-wing to different degrees (yes, Hezbollah isn't keen on leftism and had fought with the communists during the civil war; but of course, obligatory critical support yada yada).

Equally the split, unlike what bigoted orientalist journalists and correspondents claim, is not of a sectarian/religious nature and never has been. Although parties employ sectarian discourse the reality is each religion and sect has two parties or more who contradict each other and are allied with parties from different sects.

In reality, opinion is split regarding foreign policy and allegiance. Some parties are affiliated with Saudi Arabia (and by extension the US) while others are funded by Syria, and Iran. This has been the case since the establishment of the state. Historically it was the British and French. Then it was the Americans and Egyptians (Soviets by extension) which led to the events of 1958, a mini civil war of sorts. The 1975 civil war was mainly caused by disagreement regarding support for the Palestinian cause.

To clarify, this is the mainstream political narrative. But there is a class narrative which has always been overshadowed.