I passed a network class once, but it's been a while. See if this rings true for you: A router moves messages between two networks. For example my cable router sits between my private home network and the internet. A switch moves messages between devices on one network. A hub does the same with a little less smarts and efficiency.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi