I have to say that Shishido's version is the innocent version. Because Shishido is evidentally singing about ice cream and rollar skating in the park as opposed to Oshitari's sex in the back seat of his parent's car with the windows steamed up.
The audial differences of this song is VAST.
Shishido's version: YAY PUPPIES!
Oshitari's version: YAY DO THAT AGAIN!!