In North America that is more difficult to answer since other codes are nowhere to be seen.
Primarily, the High Capacity Color Barcode (HCCB) Technology in Microsoft's TAG is not an attempt to be more fashionable. It is, the culmination of significant and extensive development by Microsoft Research and some would say about bloody time too. We certainly would but we also recognize that it was more than worth the wait.
MSR designed the sophisticated technology for maximum performance in consideration of the limitations of mobile phone cameras. While some newer phones have 5 mega-pixel cameras, for most have far less. The work they have done is readily apparent the first time you try it. In fact, TAG is so fast, in automated mode, it is often is pulling down a web page by the time you realize it actually read the code.
On the Microsoft TAG's Technology page, they provide more details about the technology itself.
And that's exactly what they are. Geometric patterns and multiple colors that form a mosaic but there's also a version that uses colored dots and is being proposed as the starting point for designing custom TAGs. Understandably, MSR is not giving out much information about the precise working of the underlying technology but the real point is the performance that those little shapes allow.
Cameras on most phones today are capable of taking both pictures and video. So a key difference is which one the reader on the mobile device uses. When your phones video is used, the application is actively reading each frame and as soon as it recognizes a TAG, the application proceed with whatever action is appropriate, resulting in an excellent experience for the user.
On the other hand, when an application uses the still camera, the user must take the picture (click the button) and then wait to see is the picture they took can be read. Great when it works first time but it should be obvious that the video working at many frames per second is a big advantage.
For phones without video, there is little choice; they have to operate in passive mode. In some other cases, even when video is available, some phones must still work passively due to issues with hardware and the cameras themselves. As is always the case with new technologies, it takes a while for everyone to agree on specifications and standards, so even though Microsoft has worked to ensure TAG has the broadest audience possible, not all phones will work actively.
It should not come as any surprise that most often Windows Mobile devices and all new Windows Phones will work actively.
Not many people would remember but in the 1960's North American Railways put colored barcodes on almost all their rolling stock. Hundreds of thousands of rail cars had codes printed on them before anyone thought to do the chicken test (Tom Peters). In no time, the codes were covered by dirt and couldn't be read in the rain and ultimately the project was shelved. Had they tested the concept in real world condition early enough, they would have concluded that the systems of the day had no tolerance for error and saved a lot of money too.
Microsoft has done its chicken test. TAGs, albeit like their QR Code bretheren have been dseigned from the beginning with error correction and tollerance in mind. It would be premature of me to say which is best and certainly the market will provide the ultimate determination but damaged or disfigured TAGs can still be read (up to a point). And that point is, the technology is not an all or nothing proposition.
The difference that provides the biggest benefit is that TAGs are references. The easiest way to understand is to think of a TAG as simply a number that references something else. Just like a telephone number, or your social security number, they reference different things but are unique to you. Of course, a TAG represents a really big number but a reference just the same.
Conversely, QR Codes are graphical representations of text. The application reads the code, translates it to text, then interprets the text to determine what to do. Once a QR Code is created, its text can never change. This poses a major disadvantage. Since a TAG is always a reference, that reference can be easily changed. Just like keeping your telephone number when you change your residence, the number stays the same but it points to a completely new location.
This is an important advantage. If you put a TAG on your real estate sign, you can use it forever, over and over again.
TAGs are dynamic. If your restaurant displays a TAG for your daily special, a patron need only read your TAG once. Every day thereafter, from wherever they are, they can see what they could be having for lunch today at your establishment.
Even better, they can forwarded your TAG to their friends and make arrangements to meet. Of course being the entrepreneur you are, your display of the daily special would most include the ability to make a reservation.
TAGs can also be small. As little as 3/4" x 3/4" and so fit unobtrusively in all kinds of places without impinging on design features. More importantly, TAGs do not grow in size like QR Codes. Try filling in all the fields for your contact information in a QR Code. Don't take our word for it. Go to a site with a QR Code generator and try it. QR Codes may accommodate 7000 characters but the phone readers don not come close to that, most max out at under 300.
Speaking of that, which technology is better?