Are classes in asset browser abstract?

From oop point of view are classes in the asset browser abstract? They are not used inside the game, only their instances(objects) that are dragged into a level.
I think that all blueprint classes I create are abstract. Is that also applicable to level blueprint and character blueprint?

Bump, some educated people needed here

The asset browser is just a list of files, nothing more.
Take your Programming IDE of your choice and you’ll see a list of your source files. This is equal to your Asset Browser. Has nothing to with concrete/abstract.
It is worth mentioning that Unreal creates a so called CDO (class default object) of every class you create. Therefore not a single class is abstract in a pure OOP meaning.