It depends on the FIDE ratings of the players. If Person A is rated 1300 and Person B is 1220, A is not twice as good as B. Conversly, Carlsen is rated 2843 FIDE, and I would argue he is at least twice as good as a 2763 player (if they played 10 matches, each match 10 games long, Carlsen would almost definitely win 9/10 to 10/10 matches).
The reason for this is that it becomes harder to keep increasing as you get a higher rating. 99% of chess players are below 2200, even though there's an extra 600 points above. The trend on a graph of rating vs #players is not linear; it is closer to an exponential decay function. There are vast number of players under 1400, but only an extremely select few over 2800 at a time (usually 5 players max).
Chess is a game where most people can go to roughly 1800ish with hard and dedicated work. However, only people with true talent can continue past that point. Then, once hitting 2000, an even smaller number of people can continue forward. This phenomena becomes stronger as you climb up the rating latter, which explains why such a small percent can ever make it to GM level.
As a result, if Person A and Person B are in a high rating bracket, Person A being 80 points higher indicates he truly has an additional "special something". Meanwhile, if A and B were in a low rating bracket, A being 80 points higher could be attributed to something like playing in a few more tournaments.
EDIT - Carlsen example fixed.