Events - it's like you do marketing for your product that is not yet known by the general public, so that it can bring in new customers for your product. However, consumers will judge the product whether it is worth buying or not.
development - this refers to new technical developments that will apply to them such as hard forks, upgrades and etc. Take for example ethereum which upgraded to ethereum 2.0 where the efficiency of the network is more optimized and new features were introduced in ethereum 2.0. this will encourage more people to buy ethereum so its value increases. for ADA you can see the technical developments that will implementation to their network protocol