By conversion rates, do you mean clicks or sales? The CTR industry (and by that I mean people who "optimize" landing pages and ads) count clicks- but as the person paying for it I count sales and don't care about clicks.
Conversion means whatever the end company wants it to mean. If it's mass retail that probably means sales (like in dollar value or whatever). If it's something else it might mean account creation. If it's a very high touch sales thing it might mean initiating contact with a human sales person. And yes, it might mean clicking through to a specific part of the website (account creation is a subset of this).
Part of a successful as campaign has to be defining your metrics correctly. The closer to your actual end business goal, the more realistic your performance tracking is.
