We all know what casual means. It means ‘occurring by chance, without predictable regularity, occasional’ or ‘an offhand, unfeeling, or uncaring remark;: “Casual remarks are often made in parties.”

Causal, on the other hand, means ‘relating to any event or circumstances that brings about a result, expected or unexpected’ (derived from cause): “The heavy rains had the causal effect of raising the level of water in the dam.”