Original: The dispute was between those, such as the followers of the "Pillars of the Church," led by James, who believed, following his interpretation of the Great Commission, that the church must observe the Torah, i.e. the rules of traditional Judaism, and Paul of Tarsus, who believed there was no such necessity.
Simplified: A common interpretation is that the council came together because there was disagreement within the Early Christian community between those who believed the church must observe the rules of traditional Judaism, and Paul of Tarsus, who believed there was no such necessity.