According to an explanation at their web site the bar code has evolved from the 1D or linear bar code used on nearly everything that is produced and purchased today. A 1D bar code is placed on our library materials and scanned for circulating those items. Using lines that are not just straight but that create a mosaic enables more information to be embedded; QR codes.
This old-style 2D barcode contains the entire message in the code, so online access isn’t needed to decode it, but the barcode size will vary depending on the amount of encoded data. QR codes can be black-and-white or basic colors.
Continuing in their description the site states that the Microsoft Tag has more options in design and in the information contained within each tag.
Because Tags are linked to data stored on a server, you can deliver a more robust online experience – including entire mobile sites – and update the content any time without having to change the Tag.
Microsoft Tag offers three possibilities with their service: a tag creator, an application for reading the tag on a smartphone and a means of keeping track of usage.
All that's left is to display your tag.
The main difference between Microsoft Tag and QR codes is that all Microsoft Tags can be read by the Microsoft Tag app; all QR codes can not be read by all QR code readers. Unlike other 2D codes a Microsoft Tag is dynamic. When changes are made in the content connected to the tag, the tag does not need to be changed.
Microsoft Tags are more advanced than QR codes. Creating them is simple but the results are more sophisticated. Tags can be placed on brochures, sent in emails or posted outside classrooms sending students and parents to a Facebook page or blog.
I still think one of the best uses in the library media center is to place tags inside books sending users to an author, illustrator or book web site. For that purpose the QR codes would work just as well.
In all honesty, when I went to load the app to my phone, red flags popped up concerning what the app could and could not do to phone settings and personal information so much, that I did not load it. It seems that many applications want access to too much personal statistics for my comfort level. This is just my opinion.