Check out
this link to see the side by side comparison.
The things I see that the Geo has that the Veo doesn't:
Set safety time and depth
Gauge mode
Message Box (vs Bar graph)
twice the download memory capacity
Conservitive factor (which simply decreases your NDL, great for people like me who dive at all sorts of altitues because of where I am)
Watch Stuff: time, alt time, countdown timer, stop watch, alarm (which is covenient for me because I use almost every day at the pool when I'm swimming laps)
It's not air integrated, so it doesn't do the pressure reading or real time "How much longer you can last with this much air" calculation. But I like the fact that it counts down your saftey stop for you and it beeps for things like too fast of an assent, you've gone deeper than the range you've set it for, you've been down longer than the time you've set it for, etc. I'm not sure whether the Veo has the same features, but you could always download the manual for the
Veo250 and see. Or maybe download that manual and the
Geo's manual and do a little research into both setups.
Peronally, I've loved my Geo. I already had one of
these with the compass when I was computer shoping, so the Veo250 wasn't all that cost-effective for me. And the fact I use the watch features on a regular basis was a definite plus. That plus I can look at my SPG, see what my tank pressure is, and quickly figure out how much time I have left. I don't need a computer to tell me that I need to get my butt to the surface asap because I only have 100psi left.
So really, you should sit down and figure out what you're needing out of your dive computer. If you like the convinence of the air integration and the simplicity of the Veo (it's a two button config instead of the four that the Geo is), then go for it. If you like the extra bells and whistles of the Geo (and like me, perhaps you already have a gauge setup), then go with it.
Really, there's no wrong answer to this question. they're both really good computers.