Garmin Guidance 3.0 is most advanced navigation engine developed by by Garmin R&D team. It includes all the features of Guidance 2.0 plus predictive routing and the world’s best traffic avoidance system to make everyday driving easier. Digital 3D Traffic provides traffic updates every 30 seconds, which is 4–10 times faster than other traffic systems on the market. Guidance 3.0 is featured on nüvi 3400 series personal navigators.

Garmin Guidance 3.0 includes all the features of Guidance 2.0 plus:

• Digital 3D Traffic provides updates every 30 seconds
• InstaSearch for faster spelling searches
• InstaRoute loads maps faster than ever
• Pinch-to-zoom multi-touch interaction
• Automatic dual-screen orientation (horizontal/vertical)
• Bird’s Eye lane guidance highlights proper lane with overhead perspective
• myTrends^™ anticipates your destination based on your driving habits
• SafeText reader¹ — receive and hear texts without taking your eyes off the road
• Voice-activated navigation for hands-free operation (nüvi 3490)
• One Shot address entry (nüvi 3490)
• One Shot point of interest searches (nüvi 3490)

Garmin Guidance 2.0 includes:

• Faster routing and map displays
• Faster, more intuitive destination searches
• See and select businesses on map (no need to page through menus)
• Subscription-free traffic — live updates, re-route options
• photoReal junction view highlights proper lane for interchanges and exits
• Park position recall finds your car
• Speed limit indicator
• Automatic volume control (on devices with Bluetooth® only)
• Exit Services — know what you'll find when you exit the highway
• Voice-activated navigation for hands-free operation (nüvi 2495 and 2595)
• One Shot address entry (nüvi 2495 and 2595)
• One Shot point of interest searches (nüvi 2495 and 2595)
• Compatible with Digital 3D Traffic with accessory purchase

Source: Garmin official site