Comparison of English dictionaries

Full-size.
These dictionaries generally aim for extensive coverage of the language for native speakers. They typically only cover one variety of English.
Collegiate.
These dictionaries generally contain fewer entries (and fewer definitions per entry) than their full-size counterparts but may contain additional material, such as biographical or geopolitical information, that would be useful to a college student. They may be revised more often and thus contain more up to date usage. Sometimes the term "collegiate" or "college" is used merely to indicate a physically smaller, more economically printed dictionary.
Learner's.
These dictionaries generally contain fewer entries than full-size or collegiate dictionaries but contain additional information that would be useful to a learner of English, such as more extensive usage notes, example sentences or phrases, collocations, and both British and American pronunciations (sometimes multiple variants of the latter). In addition, definitions are usually restricted to a simpler core vocabulary than that expected of a native speaker. All use the IPA to indicate pronunciation.