Networking. Nexus One is a GSM phone, initially available in the U.S. on T-Mobile's High Speed Packet Access (HSPA) 3G network, with up to 7.2Mbps uplinks. The cellular RF transceiver is the Qualcomm RTR6285 chip which supports multiple UMTS bands and quad-band GSM/EDGE, with integrated GPS. Google promises a CDMA version will be available for Verizon Wireless. In the U.S., iPhone 3GS runs only on AT&T's 3G and EDGE networks.
Wi-Fi and Bluetooth (and FM radio) are integrated on a single Broadcom chip, the BCM4329 http://www.broadcom.com/products/Bluetooth/Bluetooth-RF-Silicon-and-Software-Solutions/BCM4329, the same chip in iPhone 3GS. The difference: in the Nexus One, support for high-throughput 802.11n is turned on, but not in the iPhone.
Photo credit: iFixit