你的问题只要查一下英英词典就清楚了：

passage：a usually short section of a book, poem, speech, etc.段落；章节

He quoted a passage from the Bible. 他引用了《圣经》中的一段话。

The book's main theme is reflected in the following passage. 这本书的主题在下一段落中得到反映。

paragraph：a part of a piece of writing that usually deals with one subject, that begins on a new line, and that is made up of one or more sentences段落

In the second paragraph from the bottom, you've misspelled “their” as “thier.” 在倒数第二段中，你把their错拼成了

Please refer to section 2, paragraph 4 for the appropriate information. 相关信息请参考第2节第4段。

passage既表示“段落”，也表示“章节”，而paragraph只表示“自然段”。如果你做阅读理解题注意一下，可能会见到这两个词在用法上的明显区别。

下面这类句子中的passage显然不是指自然段，其实是指你读的那篇短文：

What could be the best title for the passage?

What could be the most suitable title for the passage?

下面句子中的paragraph则是指自然段：

What does the underlined word “that” in paragraph 2 refer to?

On what basis do we “adjust the influence” according to the last paragraph?

What do the underlined words “the offender” in paragraph 8 refer to?