A snapshot can only be restored by creating a new instance. You cannot restore a snapshot to an existing instance. While restoring the snapshot to a new RDS instance, you can have a different storage volume type from the one used in the snapshot.
Creating an RDS DB instance from a snapshot automatically attaches a default parameter group and security group to it. Once a DB instance is created, it is possible to change the attached parameter group and security group for that instance. By restoring a snapshot, the same option group associated with the snapshot will get associated to the newly created RDS DB instance. Option groups are platform-specific—VPC or EC2-Classic.
Creating an RDS DB instance inside a particular VPC will link a used option group with that particular VPC. It means that when the snapshot is created for that DB instance...