what ：单独使用,只能引导【名词性从句】,即主语从句、宾语从句、表语从句等,意思是【什么（事、情况、内容等）】.例如：
What we need is more practice.主语从句
He told me what had happened to him on the island.宾语从句
This is what we have got from the project.表语从句
whatever ：既可以引导名词性从句,也能引导【让步状语从句】,意思是【无论/不管什么（事、情况、内容等）】.
相互转化：只有在【引导让步状语从句】时,whatever=no matter what.
Whatever happens will never change my Chinese heart.主语从句
I'd like to do whatever I can to help you.宾语从句
对比：
Whatever happens will never change my Chinese heart.
Whatever happens,it will never change my Chinese heart.
=No matter what happens,it will never change my Chinese heart.
祝你开心如意! what ：单独使用,只能引导【名词性从句】,即主语从句、宾语从句、表语从句等,意思是【什么（事、情况、内容等）】.例如：
What we need is more practice.主语从句
He told me what had happened to him on the island.宾语从句
This is what we have got from the project.表语从句
whatever ：既可以引导名词性从句,也能引导【让步状语从句】,意思是【无论/不管什么（事、情况、内容等）】.
相互转化：只有在【引导让步状语从句】时,whatever=no matter what.
Whatever happens will never change my Chinese heart.主语从句
I'd like to do whatever I can to help you.宾语从句
对比：
Whatever happens will never change my Chinese heart.
Whatever happens,it will never change my Chinese heart.
=No matter what happens,it will never change my Chinese heart.
祝你开心如意!