I recently started self-learning about GNNs, and I have trouble understanding the difference between the GNN models.
As I understand it, all GNN models apply an aggregation step on each node, and the different models differ in the aggregation function.
- Is the aggregation for a single node done by aggregating the entire graph? or only its close neighbors?
- What is the difference between GraphSAGE and other GNN models? Do I understand correctly that GraphSAGE aggregates only some of a node's neighbors and not all of them?