a variety of 意为“各种各样的”，the variety of 意为“……的种类或多样性”，两者均可修饰可数或不可数名词。如：
The audience are dressed in a variety of ways. 观众有形形色色的穿着。
The variety of his writing was astonishing. 他作品的多种多样令人惊讶。
The love of money produces an endless variety of misery. 贪财会引起无穷的不幸。
注意：the variety of后接复数名词作主语时，谓语动词要用单数；a variety of 后接复数名词作主语时，谓语动词原则上要用复数，但有时也可用单数。如：
The variety of goods in this shop is rich. 这家商店的货物品种丰富。
A variety of books have been published. 出版了各种各样的书。
A variety of reasons were [was] offered for the long delay. 为这次长时间的耽搁提供了各种各样的理由。