In an election year, the incumbent government usually presents vote-on-account in Parliament which enables the government machinery to meet important expenses of administration, like salaries etc. The vote-on-account is usually for a period of three-four months and is meant to provide a smooth transition for the next government; it gives time to Parliament when it reconstitutes after the elections to discuss and pass the full Budget and allocate money accordingly.
The Modi government has indicated that this year's Budget will not be a vote-on-account but an interim one. While the vote-on-account deals only with the expenditure side of the Budget, an interim Budget has both expenditure and receipts and gives the complete financial statement, much like a full Budget.
With 2019 being an election year, the Budget presented by the government will be an interim one as during election years the newly elected government presents the full Budget around July.