Mormon does not tell us what these contentions were, but the conjoining of two completely different language/culture sets could not have been without difficulties. We do not have mention of difficulties in the reign of King Mosiah I, either because the newness of the situation smoothed over many differences, or they simply were not reported.
Although Mormon tells us nothing except that they existed, the source material he was using surely went into greater detail. We may presume that this is a very heavy handed editorial, preserving the essence of the problems without discussing the specifics. They would appear to be significant, because this verse is in the transition, and has no real function as a transition. If there were minor contentions, they would not have been worth mentioning.