Is revenue the same as budget?

No, the revenue is not the same as the budget. Revenue is the income generated, whereas budget is the amount that is available, which can be used for meeting the necessary expenses. You can read about the Union Budget 2021 Summary in the given link.

Further readings:

1. Difference between Economic Survey and Union Budget
2. Previous Years Economics Mains Questions in UPSC Civil Service Exam, General Studies Paper – 3