It is a little hard to tell in the photo, but the ring on the left is yellow gold and the one on the right is champagne gold. The rings are also made in 3.5mm and 3.0mm widths; the difference of 0.5mm gives a very different impression when you put the rings on.
You can try on samples on the day of the event and make your selection.
Handmade wedding bands in champagne and yellow gold