What is the difference between VK11 & VK31

VK11 is to maintain a single condition record and VK 31 is to maintain a group of condition records according to the situations.

In vk11 you can update for particular condition record, whereas in vk31 you can do the Mass changes.

The bottom-line difference between VK11 and VK31 is that VK31, VK32 ONLY work for standard SAP delivered Condition Types (ex. PR00).

If you create any customer specific Condition Type codes (ex. ZXXX) you can only create / maintain Condition Records for them using VK11, VK12.

BOTH transactions allow mass entry and changes.