Viral: when a marketing campaign takes on a life of its own.
Social: using social networking applications in your multi-channel (email/site/direct mail) campaign.
Viral example: almost anything that use a trope or motif that is embraced and reproduced by others, at no cost or expense by the company involved, such as, BlendTec
Social example: A marketing campaign that uses new social applications and existing social networks, such as Facebook, Twitter, etc. to further its goals. Example: Zappos.
I can’t tell you the number of times I have attended a conference seminar or read an article that was completely misnamed- not viral at all- and thus has been mis-used and abused in all of the time that has passed since it’s introduction. It’s not it’s fault, but the definition has been muddied.
Because I consider very specific social marketing being the use of social networks and social network tools- Facebook, Twitter, FourSquare, etc. Viral has actually been around for a while, back to Guerrilla Marketing days, back to the “pay someone’s toll and add your business card.” Social marketing could be very un-viral, hiring interns to tap away twitter messages all day. Viral marketing could avoid all uses of social network tools- see example of business card at the toll booth.
Well, the distinction is muddied because most, if not all, social marketing campaigns aspire to viral. We all want to be the BlendTec of [insert your industry here].