Official Raspberry Pi Page
https://www.raspberrypi.org/products/raspberry-pi-3-model-b-plus/
Key Differences To The Raspberry Pi 3
1.4GHz 64-bit quad-core processor (Broadcom BCM2837B0, Cortex-A53, ARMv8)
Dual-band wireless LAN
Bluetooth 4.2/BLE
LAN7515 6-port USB 2.0 hub (4x usable) with 10/100/1000 Ethernet replaces previous LAN9514 integrated 4-port USB 2.0 hub and 10/100 Ethernet. (maximum throughput 300 Mbps over USB2.0)
Power-over-Ethernet support using separate PoE HAT.
Shared Specifications To The Raspberry Pi 3
Identical form factor to the RPi3, RPi 2, RPi1 Model B+.
Complete compatibility with Raspberry Pi 1 and 2.
1GB RAM
4 USB ports
40 GPIO pins
Full HDMI port
Ethernet port
Combined 3.5mm audio jack and composite video
Camera interface (CSI)
Display interface (DSI)
Micro SD card slot