In terms of the laser itself, an audio CD might wear more because it's constantly reading.
But remember some games do constantly read audio and data when you're playing them too.
In terms of the mechanics of the CD drive I should imagine that audio CDs would be 'kinder' to the drive because they are linear; there's no jumping back and forth on the disc seeking data. Don't know about VCDs as I've barely used them, but I'd imagine they're the same.
Watch out with saturn vcd cards because your laser needs to be in very good condition otherwise the audio and video will go out of sync.
I have tried my card on both my saturns whos lasers are fine on games and audio cd's but sure enough - they are not strong enough to read the vcd's. After about 20-30 mins they go out of sync. I isnt a problem with the discs either as i have tried them on other players and they are fine.
Technically, to call it a "VCD" the bitrate must never be higher than 1150kbits (at least i think thats the magic number - always forget that one...). Anything higher and it's put under the blanket term "XVCD". 8 bits to the byte, so thats ~143kbytes a second, which is approximately half what the Saturn CD drive is technically capable of.