blu tooth is just a 2.4 ghz radio protocol. to pair up blu tooth devices, like headsets and phones, headset and computers or speakers or about any audio device you want to pair up instead of using wires. Typical ranges are about 30 feet, but some can go further. Even my 2010 Silverado pickup truck has it. You can get in with your cellphone and it will want to pair up the phone with the audio system in the truck.
The "Cloud" is way more complicated. One application of the "Cloud" would be just "cloud" storage, where you buy data storage space on some server, and you have good data connection speed to that location to keep all your data off site for disaster recovery purposes. You can also do "cloud computing" to have your processing power offsite. and just run a client at your local site.. Lots more too..Cloud networking to connect all of your sites... etc. It is all just "in the cloud" man!