Commercially speaking they are the same, as stated by Wikipedia, but what should be the correct way to name our precious personal devices?
In the October 4, 2011 Special Event, Apple CEO Tim Cook introduced the sales figures for computers by calling it the Macintosh (source: http://www.apple.com/apple-events/october-2011/). He subsequently referred to it as the Mac, but if the company CEO still uses the term "Macintosh" I'd say the name is not defunct.
Im pretty sure Mac is the preferred term now, and usually when they are being discussed, the type of Mac is usually mentioned (iMac, Mac Pro, etc). Professionally they are usually addressed as Macs vs Macintosh as well. Either way you would be right.
Though, on some of the newest packaging, my new iMac box said 'Apple Macintosh' on it. And in some of the paperwork, they use Macintosh and Mac interchangeably.
I have noticed for many years that people who do not own or use a Macintosh (and aren't quite sure what one is) refer to them as a "MAC" in all capital letters, whereas people who actually use one always refer to it as "Mac".
This is an easy way to tell whether or not the person whose article or post you are reading has any idea about what they are saying.
"MAC", on the other hand, is an acronym for "Machine Access Code address" and refers to the unique hardware identifier of every Ethernet and WiFi network card in the world. So every (networked) computing device has its own MAC whether it's a PC, a Mac, an iPhone, or something else.