In the IETF RFC draft named "SM2 Digital Signature Algorithm" a signature algorithm is specified. The RFC does however not mention why this signature algorithm has been defined. Nor does it specify what the advantages of this scheme are over ECDSA. It seems that SM2 is the preferred EC signature format in China.
So the two related questions are:
- Why was SM2 defined?
- What are the (operational) differences compared to ECDSA?
Note that there seems to be a set of SM2 Elliptic Curve domain parameters defined as well.