There was the following line in December 2nd AP News,
“Chief White House trouble shooter for healthcare gov.web site says the web site is night and day from where it was October 1st. Jeff Zients say they carried out hundreds of software and hardware fixes.
I first took “night and day” for “continually,” but later realized it meant the status of web site is compretely different (mproved) from October 1st stage after searching for the definition of “night and day” other than “all the time,” and found it in Online slang dictionary and urbandictionary:
While all major dictionaries only provide ‘all the time” implication, both Slang Dictionary and Urbandictionary provide “completely different” implication as shown below:
Cambridge Dictionaries Online:
night and day (also day and night) all the time: [ex.] They've worked night and day to publicize their campaign.
all the time; constantly: [ex.]She studied night and day
all the time: continually
unceasingly; continually: [ex.] She worked night and day until the job was done.
The Online Slang Dictionary:
A phrase used to describe a stark difference between two things. Similar to day and night, except it implies an improvement of the situation rather than a deterioration.
So my question: Is the usage of ‘night and day” in the meaning of “completely different” popular, or still on the sideline? Because I don’t find it in any of Cambridge / Oxford / Merriam –Webster English Dictinoary.