含義和用法上，a great number of 與 a great many of 有著細微的區別。a great number of 用來形容大量的可數名詞復數，它強調的是數量多，類似于 plenty of 或 a lot of 的用法。比如："A great number of water fowls dwell on the island." 這句話意指島上棲息著許多水鳥。而 a great many of 則強調的是某一范圍內的很大一部分。它表示的是比例，類似于 a large part of。例如："A great many people are often willing to sacrifice higher pay for the privilege of becoming white collar workers." 這句話的意思是，許多人常常愿意犧牲較高的薪水，以換取成為白領工人的社會地位。進一步來看，"A great many of them are graduates of special training schools for die-hards." 這句話中的 a great many of 強調的是頑固分子中很大一部分人擁有特殊培訓學校的背景。最后，"Now a great many of them are out of work." 說明失業的人群中很大一部分人面臨就業困難。而在財政補貼方面，"Total agricultural subsidies in 2009 were around $16 billion, which would pay for a great many of the ideas that follow." 表示2009年的農業補貼總額約為160億，足以支持許多后續的想法實施。