1. 楼主的这种说法可以,只不过需要更加准确一点：Ving做定语可以转换成定语从句（包括非限制性定语从句）,它们都做后置定语.
其实过去分词/不定式等其他成分做定语时,也可以转换成定语从句来表达.
如：There are many things for us to do.
= There are many things that we should do.
2. 分词作状语时,也可以换成定语从句（包括非限制性定语从句）来表达.
但是,其在句中的语法功能就变了.毕竟一个是状语,一个是定语.
如：Hearing the news, Tom felt excited. （Hearing the news为原因状语）
可以换成：Tom, who heard the news, felt excited.(who heard the news为非限制性定语从句)