I don't have a 2.0 so this info is from current marketing and reviews. It appears to me the gun has been tweeked for range and competition use. Some of the new features are less desirable than the original version for concealed carry, IMO.

There are two models available currently, the standard 4.5" barrel and the 5". There are slight differences between the two. They are both backwards compatible for mags, holsters and iron sight options. Both share the same recoil spring assembly (RSA) despite the different length barrel/dust cover. Only a limited number of versions are currently available.

Modifications both have:
Sharp grip stippling
Slight mag removal cutouts on each side at bottom of grip (which do not appear to align with similar slight indentations in the mag floor plates)
Four palm swell grip inserts
Shortened Beavertail
Different barrel lockup dimensions (tighter)
An extension of the stainless steel frame forward into the dust cover to further stiffen the frame
Extended slide frame rails up front for better slide stability
Differently machined slide [not compatible with 1.0?]
Lightened slide profile
Forward slide serrations (kind of)
Dust cover windows
Removeable ambidextrous safety
Improved trigger bar/sear interface with lighter trigger pull, better reset
Substantially different ambidextrous slide stop (to eliminate auto-forwarding) [New patent applied for; Different and more limited operation basically requiring overhand operation (slide retraction) as primary slide release method]

The 5" version has a long Loaded Chamber Indicator (LCI) on the top of the slide [Precludes mounting a red dot sight].
The Flat Dark Earth (FDE) model slide is Cerakoted over the standard Armornite (salt nitride hardening) black finish.


http://http://www.range365.com/smith...-20-gun-review

M&P(R)9 M2.0™ | Smith & Wesson