The only difference being that there are twice as many elements being charted. Visually a synastry chart looks exactly like a birth chart - a 360 degree wheel divided into 12 sections. Basically it is overlaying two individual’s birth charts and examining the aspects between the two charts. Now when we overlay another individuals map over your map, we can visually see where their planets were located in relations to yours - that is the basis of a synastry chart.
Think of a map of the cosmos that is a snapshot of the exact planetary coordinates of when you were born.
