Version 1.1 and earlier
Since the technology of Bluetooth was introduced in 1998, several specification versions have been released. Versions 1.0 and 1.0B had too many issues and problems for manufacturers to develop devices for Bluetooth. The main issue was the lack of communication among the devices.
The core specification version 1.1 is the first successful operating version of Bluetooth. Version 1.1 corrected a majority of the bugs and problems found in earlier versions.
Many of the newer Bluetooth devices, such as the newer cell phones are being sold with the newer Bluetooth version 1.2. This version offers backward compatability with Bluetooth 1.1, faster transmission speeds, received signal strength, and a host controller interface (HCI) support for 3 wire UART.
Bluetooth version 2.0
It's true that there may be multiple communication technologies, although they all share one common trait - faster is better. Bluetooth specialists realized this, and therefore worked on improving the speeds of version 1.2. The newest version, version 2.0 + EDR (Enhanced Data Rate) was accounced in 2004 and became available in late 2005.
Version 2.0 delivers data transfer rates of up to three times that of the original version of Bluetooth. Version 2.0 also provides enhanced connectivity. With Bluetooth 2.0 + EDR, you'll be able to run more devices at the same time - with more efficiency.
Computers and even computer related devices are expected to be some of the first devices to encorporate Bluetooth 2.0 + EDR, followed of course by audio and imaging devices.
Version 2.0 is backward compatible with previous versions, three times faster, and offers an enhanced data rate of 2.1 MB a second. It also offers broadcast and multicast support, along with a further enhanced bit error rate performance, making it the best Bluetooth has ever seen.