Most probably, NOTHING.
What was shown in pre-eligible or pre-approval stage is TENTATIVE (and it was only an indicative figure - before processing).
What is communicated along with the Card is the FINAL after your application was processed.
So, don't waste your time on such things. Use the card for atleast 6 months and then ask for limit enhancement - with your ITR and salary income slips. The bank may consider it favorably.