If you had to narrow the difference down to some key points, what would be a simple difference between a viral campaign and a social media campaign? Actually engaging users.

In China, Lenovo was promoting its new kind of netbook, the Ideapad S10, through a social media campaign using BBS, QQ emotional icons, video, widgets, etc:

A lovely Kuku Bear is the brand image of S10, therefore Lenovo mainly promoted this bear image with some touching love story. [...] Its video on Youku was viewed for over 1.7 million times, its application on Xiaonei.com ranked No. 6 most popular apps on the platform, with about 58,000 daily active users. And its sales on Taobao shop is quite good.

Yes, the marketing campaign succeeded and in fact the viral campaign (the part of it that is) succeeded, but in terms of a social media campaign it was a complete failure (minus any comments on their application page, if any, on Xiaonei).

Hopefully the advertising agency or marketing department was not a functional team calling itself social media marketing as they do not understand the meaning of social media then.