See into S60 Blog has a good summary of the differences and changes in the various S60 editions.

S60 1st Edition…
- Java? 2 Platform, Micro Edition (J2ME?) APIs, including:
- Mobile Information Device Profile (MIDP) 1.0.
- Connected Limited Device Configuration (CLDC) 1.0.
- Wireless Messaging API (JSR-120).
- Mobile Media API (JSR-135).
- XHTML/WML browsing.
- Multimedia Messaging Service (MMS) messaging.

S60 1st Edition, Feature Pack 1…
- The introduction of Java? APIs for Bluetooth Java Specification Request (JSR-82) to S60 1st Edition, Feature Pack 1 is a notable addition.

S60 2nd Edition…
- Skinning (theme) and Digital Rights Management (DRM) C++ APIs.
- Java? 2 Platform, Micro Edition (J2ME?), Mobile Information Device Profile (MIDP) 2.0, including enhanced performance through the inclusion of the Connected Limited Device Configuration (CLDC) HotSpot compiler.
- XHTML browsing over TCP/IP.
- Multimedia Messaging Service (MMS) support for HTTP transport and advanced presentation capabilities through enhanced Synchronized Multimedia Integration Language (SMIL) support.
- Open Mobile Alliance (OMA) Client Provisioning, which allows device settings for services such as browsing, MMS, and over-the-air (OTA) Calendar synchronization. This technology enables easy device configuration and ensures that a consumer can take full advantage of a device?s capabilities.
- DRM via OMA forward-lock.

S60 2nd Edition, Feature Pack 1…
- Presence Open and Bluetooth notifier C++ APIs.
- Wireless Messaging API 1.1 (JSR-120) and Mobile Media API 1.1 (JSR-135) Java? APIs.
- Support for a megapixel camera with 4x zoom as well as recording and playback of video clips.

S60 2nd Edition, Feature Pack 2…
- C++ APIs for browser plug-in, connection monitor server, Digital Rights Management (DRM) license manager, simulation file, DRM helper, pictograph, DevASR, speech recognition utility, MMF SRS custom commands, Data Synchronization Profile Listing, content access framework, GIF scaler, Huffman encoding and decoding,
message queue, Publish & Subscribe, Location Acquisition, OpenGL ES, EGL, and Symbian XML framework.
- Mobile 3D Graphics API for J2ME? (JSR-184), FileConnection API (JSR-75), and PIM API (JSR-75) Java APIs.
- Support for a 1.3-megapixel camera with 6x zoom, WCDMA and Enhanced Data Rates for Global Evolution (EDGE) networks, and IPv6.

S60 2nd Edition, Feature Pack 3…
- APIs for feature discovery, scalable icons, browser control, download manager user-interface library, download manager engine, image transform library, image transform plug-ins, Universal Serial Bus (USB) client driver, and an updated utilities API.
- J2ME? Web Services Specification (JSR-172) and Java APIs for Bluetooth (JSR-82), with OBEX support Java APIs.
- Support for scalable user interfaces (176 x 208-pixel, 240 x 320-pixel, and 352 x 416-pixel screens).

See into S60 Blog