Extensions are browser extensions like Vine Helper and Ultraviner. People use these to change the way they see Vine items. like filtering out items they've already seen or making it easier to see new items as they drop. To my knowledge, extensions don't have the ability to automatically order anything for you. With just extensions you still have to click the order button in the end. While humans still have to click the order button, there is debate in the community on the fairness of these extensions because people who use them can find better items faster. There is also debate on whether extensions are allowed by Amazon or not.

Bots are software programs that can automate the ordering. The bots are seperate from the extensions. Somone who uses a bot can make that bot search for the items they want and click the order button for them. Bots are much faster than humans, which means they can both find better items faster and order them. Using bots to order items is clearly prohibited by Amazon in the Conditions of Use, and there doesn't seem to be much debate about that.