Traffic Source – Conditional Post Template

Not entirely sure if this is the right forum to ask this, but:

Does anyone know if there’s a way to show a different post template (not page template) dependent on where a visitor has come from?

E.g. if I wanted to use post template A for all normal users, and post template B for all visitors from a specific source such as Adwords?

The logic seems simple enough – If source=adwords use post template B, otherwise use template A, but I just can’t figure out how to do it…would it even be possible?

Thanks in advance.