Originally Posted by
Xherion
Edge 200 doesn't have a barometric altimeter, so it uses the public elevation mapping data. Higher end Edge's have an altimeter, so all things equal, they are generally more accurate assuming the weather and temperature don't fluctuate significantly while on the ride. Even among devices with altimeters on the same route, it isn't uncommon for a ride to differ by a couple hundred feet. I wouldn't get too hung up on it.
I've also found that if you're riding at sea level the elevation is absolutely worthless. I'm in south Florida and my rides are way off, giving me 1500 feet of climbing on absolutely pan flat roads and even when temp and pressure stay constant I get several hundred feet of climbing. I'll be interested to see how it works in the mountains later this month.