From what i understand, the distinction is between the signing up
to the site. So you sign up to pokerstars
and use the marketing code cardschat and are therefore tracked to cardschat during your signup. Then when you deposit you don't use "cardschat" as a bonus code but instead you use the "first2008" or whatever Stars is using now, but since you were originally tracked to cardschat you get the extra bonus.
The stars bonus is so bad tho...i believe it is 100% match to a maximum of $50. At a 50$ deposit it takes forever to clear given the stakes you are able to play with such a BR. I've made ~500$ since i signed up a little over 2 weeks ago at stars and i am barely
over half way to clearing my bonus. I don't even care about the bonus now it is so small :S