The Glo's resolution is definitely higher than the Touch's. Some argue that there is noticeable difference in person (myself included) while others disagree, but there is, at the least, a difference on paper.
It's also been pointed out (I've also noticed it) that even with the light
off, the Glo has a slightly whiter background than the Touch, which theoretically improves the contrast, but will probably not make much of a real difference in practice.
Tkavan, when I was considering purchasing the Glo, one of my main argument against the purchase was that a better reading experience in bed (approx. half an hour a day) does not justify the upgrade. But I happened to stumble onto some extra spending money at the time and thought what the heck, but like a lot of other Glo users, I read with the light on at all times, which significantly increases the contrast and "readability". Not sure if this was the reason for your question, but if it is, you should consider this.
Edit: Found the poll I created a while ago on Glo user preference, 16 of the 59 people who answered this particular section of the poll said they have the light on at all times, with only 7 responding that they turn it on only when it is not readable without it (others, of course, falling in somewhere between these extremes)
https://www.mobileread.com/forums/sho...d.php?t=195789
link for the poll if you're interested.