I think the fight depicts a 90% gap or so. Tao decides to get serious and charges at Goku with a kick. Goku blocks it -- albeit with effort -- then blocks his punch -- now we can't see his face -- and taking advantage of an opening manages to connect a kick on Tao's face, who seems really annoyed. Goku's happy seeing he still has the advantage against a serious Tao. This latter charges at Goku with a kick, who dodges, and then Tao does use the ground to throw himself at Goku, managing to finally a connect a punch, which visibly annoys Goku a bit, who then counter attacks punching Tao and using the ground to propel himself at the assassin and kick him into the ground.
Tao Pai Pai is visibly annoyed and decides to use his Dodonpa (by "now I'll get really serious" he probably meant the Dodonpa) and then, upon a lot of effort, Goku manages to block it (although his hand is still aching and a little burnt)... Tao wonders whether Goku's a monster and resorts to the sword, forcing Goku to use his Nyoi-Bo and break out Tao's sword. Goku then gives Tao the freebie, who connects many punches (the sequence of blows remembers me the attack Tenshinhan used against Goku in the 22nd Budokai, btw) and then finishes the attack with a blow that really seems to hurt Goku based on this latter's eyes popping up. Goku gets up with cosmetic damage, smiling and compliments Tao Pai Pai, saying those attacks hurt him... Tao is flabbergasted since he expected them to have more of an effect and can't believe what's happening. Goku then goes on to punch Tao into the gut (to which this latter is visibly in pain), karate-chops his neck and then kicks him into the ground. And then Tao Pai Pai concluded he doesn't have a chance against Goku in a h2h combat and resorts to the bomb, to which Goku, using an incredible speed, kicks it upwards, hitting Tao instead.
So that's the fight. Whilst Goku has obviously the advantage and it's folly to claim both were pretty close, I don't think the fight depicts a humongous gap given Tao still manages to land a punch on Goku, can hurt him with his sequence of attacks, gets complimented by Goku and forces him to put up some good deal of effort when defending himself from Tao's attacks.
I think Tao might be even closer to Goku than Zarbon was to Vegeta or than Kk Goku was to 18k Vegeta, so a 90% gap seems fair here to me. Goku's a couple of steps ahead of Tao, but Tao can still keep up the fight going for some moments.
