can't help doing 和can't help but doing的区别

问题描述:

can't help doing 和can't help but doing的区别

can't help doing是情不自禁地做什么事情
can't help but doing好象正确的应该是can't help butdo sth意思是不得不做什么,不能不做什么 e.g.:(I cannot help but be sorry.我不能不感到遗憾.)