yeah there aren't many similarities...
apblu is visual novel packed with a lot of text, while this sao game is more about the experience, each individual heroine seem to have a standard plot, like for example: suguha and the playboy using some ridiculous blackmail, asuna and the fugly have a similar plot often used in mom ntr, milf with the ugly pitiful kid, using pity to gain sexual favors.
but when you combine eveything together it turns out to be a captivating experience, i just hope it won't be rushed and end too soon.