不同点：
what he said is very imporant 的表达是正确的,而 he said is very important 的表达是错误的.为什么这句“he said is very important ”表达是错误的因为 is 没有主语；在英语中，一个谓语动词应对应一个主语（并列谓语、并列主语的情况除外）