I would say at their respective peaks Tsonga had the better achievable skill cap in terms of how effectively he could maximize his strengths and hide his weaknesses, because on his day his level could beat almost anyone, even on their strongest surface. Federer on grass, Djokovic on hardcourt. Maybe not Nadal on clay but pretty much anything else you could throw at him.
Roddick had the better consistently achievable skill cap. Roddick had much better shot tolerance for the majority of his career and also a better returner, particularly on the backhand side.
The biggest difference for me in their games is how similar they were as younger players, but how much their styles bifurcated as they decided to tailor their games very differently over their careers, and how that worked out for them longterm as the game changed.
Tsonga decided to weaponise his Strengths, getting bigger, stronger and more aggressive. His weakness were glaring (backhand, backhand return) and arguably got worse. His peak level remained absurdly high but he drifted in and out of the tour for years at a time.
Roddick played it safe, and obviously saw the writing on the wall with the incoming slowcourt era. He essentially did the opposite of Tsonga, and became an Uber-steady grinder with a huge serve. Roddick hedging his bets effectively ended his ability to peak anywhere near what Tsonga was capable of, but his long term consistency was incredible.
I admire both players for the paths they took. I think in Roddick’s case he made the right move, and I think Tsonga’s approach was right for him too. JWT is a huge man, a career grinding it out in the vein of Roddick would have been too hard on his body. Staying streaky and ultra aggressive made him a fan favorite anywhere he went and gave him victories that he wouldn’t have got elsewhere if he was forced to defend and work points from his backhand side more.