In the Cambridge Grammar of the English Language, Huddleston and Pullum use the term "determinative" for the lexical category of words like the, etc. And they use "determiner" for the grammatical function that is characteristically filled by determinatives (but which can also be filled by things such as genitive noun phrases).
In an older generation of reference grammars, however, notably Quirk, et alia's Comprehensive Grammar of the English Language, the use of these terms is exactly reversed. That is, "determiner" is the lexical category and "determinative" is the grammatical function.
The difference has been bugging me for a long time. Can anyone provide a principled explanation as to why we should prefer one over the other? I'm sure Huddleston and Pullum had a motivation to alter terminology that's been in use since Bloomfield's day, but I can't find any discussion in their work.