Are you sure you read that, correctly? It looks like the TOTAL weight for the first one you link to is 22g. The second appears to be 30g (and this might be explained by the fact that they make different sizes for different arrow sizes). Wouldn't you THEN have to subtract (presumeably) the wieght of the standard arrow nock to see what (if any) the difference is?

Am I looking at this, wrong?