How many words occur in the works of Shakespeare? The question may be asking how many types of word, or in other words how large Shakespeare's vocabulary is, in which case the answer will be several thousand, or it may be asking how many tokens of those types, or words as they would be counted by a printer, in which case the answer will be many more. A car manufacturer may produce half a dozen cars in a year (types, here equivalent to models) but many thousand cars (instances, tokens). Types may themselves be subject to different criteria of individuation : lexicographers need controversial principles in order to know when to count one word type or two.
Philosophy dictionary. Academic. 2011.