Design
4S: Glass, plastic, steel
5: Glass, plastic, aluminium unibody.
SIM
4S: micro
5: nano
Screen
4S: 3.5" 640x960 IPS
5: 4" 640x1136 IPS with 99% sRGB coverage
Camera
4S: 8MP BSI sensor MAX ISO800, 1080p video
5: same as 4S with ISO3200 and low light dynamic mode, better stabilisation
Front camera
4S: VGA
5: 720p with BSI sensor
Processor
4S: A5, dual core 0.8GHz, 512 RAM, dual core 543MP2 GPU
5: A6, dual core 1.3GHz, 1GB RAM, triple core 534MP3 GPU
Wireless
4S: 3G, DC-HSPA+, Wi-Fi
5: 3G, DC-HSPA+, LTE, Wi-FI (a/b/g/n 2.4 & 5GHz)
That's all I can think of now.