Note: This question is not about "fewer" versus "less."
I noticed this sentence in CMOS:
There are two fewer food groups in the new pyramid.
If I have 10 items and my friend has 12, which of these do I say?
I have two fewer items than they do.
I have two items fewer than they do.
Does the order matter here? Do different style guides encourage the use of different orders?
Either is grammatical, according to the Cambridge Grammar of the English Language (Huddleston and Pullum 2002).
The comparative determinatives more, less, fewer can occur after the head provided there is a determiner. Thus we have a post-head alternant for one more day but not for more days: compare [One day more]/*[Days more] will be needed.
(Underlining in the original replaced by brackets, p.445)
I haven't yet found a style guide that addresses usage of the two word orders.
Here is a Wordreference thread about " I ran 2 more miles than her" vs. "I ran 2 miles more than her".