Bluetooth is a wireless technology for connecting electronic devices to each other. For instance there are Bluetooth Headphones, Bluetooth Cell Phone Ear Pieces, etc...
If you want to be able to use the Bluetooth Ear Pieces with your cellphone, your cellphone must be Bluetooth compatible.
WiFi is a method of connecting to the internet wirelessly. For instance many big cities may have "WiFi Hotspots". If you are in these WiFi Hotspots and you have your laptop or any other device that can connect to the internet wirelessly, you can surf the web wirelessly as long as you are in that particular area.
And Blu-Ray is Sony's High Definition format disc. The difference between Blu-Ray and Regular DVD is that Blu-Ray can produce 1080p HD quality picture and Blu-Ray can hold more data. A Single Layer Blu-Ray disc can hold 25GB and a Dual Layer DVD can hold 50GB. A standard DVD can only hold around 8.5GB total.
Basically if you have a HDTV, Blu-Ray would be the best choice for getting the best picture quality with clear, crisp viewing quality.