Instanced Static Mesh vs Same Actor in Outliner

When we use instanced static mesh component, we can specify the transformation and can achieve on drawcall for the whole instanced static mesh component. Can we assume the same, when I drag&drop 1000 elements from the content browser into the level? I know that the outliner get’s a little messy and eventually slow but in terms if instancing during the game, will there be a difference between using instanced static meshes or relying on the automatic bundling of same objects in the outliner?

i dont know all the details but from what ive heard from the training streams with ian shadden there is a big difference when using instanced static meshes vs normal ones. the engine groups like things when using normal meshes but it still has a draw call on each one. with instanced static meshes he said it was something like 2 draw calls total when he spawned in 100 instanced static meshes