Ultegra vs 105 pedal?

Just wondering what is the actual difference between those two pedals 6620 vs 5620?? The geometry and material looks the same, the ONLY difference that I notice is the 15gram and also double the price. Any thoughts?

Materials, probably better quality bearings and a wee bit weight. I'd go for the 105 pedal(as I bought the Speedplay Chrom-moly Zero, not the stainless).