What is difference between input tax credit u/s 11 and 12?

Since Gujarat VAT came in force on 01.04.2003, hence there are two sections containing provisions for input tax credit.

Section 11 covers the input tax credit on such goods which are purchased on or after 01.04.2003 i.e. after the enactment of VAT Act.

Section 12 covers the input tax credit on such goods which were purchased by the registered dealer and were lying in stock (including stock in the process of use of manufacture) as on 31.03.2003 [i.e. before the enactment of VAT Act. Section 12 provides that the registered purchasing dealer shall be allowed to take credit on tax paid on such stock provided he submit information within the period as may be prescribed to the concerned authority containing the information regarding the quantity of such stock and the amount of tax paid on such stock.

In short Section 11 deals with the input tax credit on goods purchased on or after 01.04.2003 and Section 12 deals with the input tax credit on goods lying in stock as on 31.03.2003.

source -> https://www.commercialtax.gujarat.gov.in/vatwebsite/download/act/VAT_2005_Eng.pdf