Lets look at that gold analogy some more.

The situation is you have one person hand delivering gold from Rome to Naples.  This is bitcoin.

On chain scaling:  Person makes the gold into jewelry so they can carry more, they can wear a bunch of chains and wear a bunch of rings etc.

Off chain scaling:  The person carries gold IOU's so the gold doesn't actually have to move at all.

Clone scaling:  You get 15 people to carry the gold instead of one person.