more important 是 形容词 important 的比较级，在句中一般充当定语，表语或者宾语补足语。 more importantly 则是副词 importantly 的比较级，在句中一般充当状语。
如： In world trade, English is more important than Chinese. 表语 = In world trade, English is a more important language than Chinese. 定语 More importantly, English is easier to learn than Chinese. 状语
