Not the same material. Sport Bands are fluoroelastomer, Solo Loops what Apple calls „liquid silicone“. The Solo Loops are thinner, lighter, softer and - obviously - way more stretchable. Width is the same.
At first I thought the solo loops were an improvement—light and soft and no hardware so match any color watch. But then I realized my wrist sweats so much more with the silicone of the solo loop, and I’ve even gotten heat rash in an extreme circumstance (moving in July).
They definitely don’t feel the same. The solo loop is silicone and the soft finish wears off within a couple weeks and it gets kind of sticky. I bought my series 7 with a solo loop and I only wore it for a month. I got a regular sport band and I find it perfect.
Yeah, I find I sweat more with solo loops and they wear much more quickly whereas with the sport bands, these are really comfortable and still look new after many years. Solo loops do get more lint as well. No such issue with the sport bands.