Huruf Muaqatat
A wall being called a wall is different. God has called these surahs something for a reason. If the research is correct then AlifLaamMeem is telling us to take heed of how God has purified the bani Israel (or commanded them towards purity) and how we should do the same. Everything in the Quran should have a strong basis and not be arbitrary like a wall being called ‘wall’