1969 horn buttons

[x66 714]

I have 2 sets of horn button for the standard steering wheel. One has a light pebble grain & the other is more of a camera case grain. They both have the same casting numbers. What makes them different? My car has the wood grained center bar & I purchased a steering wheel with the grain. I studied the section on wheels but I didn't see any mention of this. Thank you, Joe