I Am Looking To Get An Auto Gps And I’ve Narrowed It Down To Garmin Nuvi 260w And 255w. Whats The Difference?

They seem similar so I can anyone tell me which is better? Assume both are roughly the same price.
Also, although its use is primarily for auto-navigation, I’ll also be using it for light GeoCaching. Is it possible to input coordinates in either?
Thanks!