Version 2.0 features a new antenna and software.
The new antenna is more sensitive than the previous version and it has better detection range than the previous version.
The new software has improved logic to reduce false positives (especially with a more sensitive antenna) and it now features 6 different modes, City, City No X, City No X & K, Highway, Highway No X, and Highway No X & K.
You'll also notice that it has a different looking connector. It's now an in-line connector, which makes it easier to plug the unit in and out with gloves on. It is compatible with the old style wiring harness, but old detectors are not compatible with the new style wiring harness.
We've also made changes to the internal structure of the unit so it's more durable as well.
Hope this helps.