User blog comment:Emptylord/Wikia discussions/Ability Infobox/@comment-7709681-20150816163358/@comment-7709681-20150816221112

For the explanation's sake, Basic means the general details of abilities, like those I mentioned in the first comment (Details about Spellshield, Spellvamp, On-Hit application, Wind Wall/Unbreakable, Blind/Parry/Blocked/Dodged and Center-to-Center/Edge-to-Edge, like at the top of the ability's details), and Additional as the More Information section of an ability, explaining specific behavior of the ability.

Oh well, I may be wrong. :P