It’s funny that I happen to have both of these mouthpieces for my alto and soprano, which are all no. 6 and both horns are SML’s! Can there be any better comparison??
And the answer to the question is: There is no answer. I totally agree with Dave Dolson about most being player related. However, I would add to that the reed issue. Often people post these comparisons (also on YouTube) using the same reed. First, I thought it was OK, but recently I have less confidence it that kind of comparison. The mp’s play differently with brands or types of reeds. So one brand and strength of feed can be good on this mp and another on something else.
The lesson here would be: Before you run to buy a new mp, try as many reeds that you can on your mp. You might find out some quite new properties. I experienced this just lately when I bought a Rico Metalite (M7) for my bari. I was really impressed about its playability. However, I didn’t like the sound very much. I was playing 3.0 Vandoren Java (red box). Then I switched to 2.5 Rico (orange box) and the sound became very nice. Full and warm with strength.
Mouthpiece comparisons are not trivial at all. It’s like controlling an equation with too many variables. The best thing I can advise is patience and that is coming from someone with a serious mp syndrome constantly looking for something new.