PCs have about 2.5 GHz processor speed, with at least 2 GB RAM nowadays, graphics accelerators and at least 320GB hard disk. It would run Windows or Linux or MAC OS.
But RPI has 700 MHz processor speed, with 256MB RAM (in ver A) /512MB RAM (in ver B) and uses SD card as hard disk. Because of the limited hardware features, RPI would not run a heavy OS. Instead, a light weight OS can be run.
Let me elaborate the functional changes. You will be able to run heavy software like photoshop, MATLAB, MAYA etc on your PC. But RPI is too weak to handle them. RPI is most suited to run light weight software. So we call it "embedded systems".
I have some suggestions about what you can transform a raspberry pi into.
- You can connect RPI to your TV, give an internet connection to RPI and use your TV to watch streaming videos or browse. Sit back on your sofa, use a wireless keyboard and mouse and use it as a computer for browsing and playing videos..!! Like this.
- Put RPI in a proper enclosure with small display unit and small keyboard to make it a portable computer like this.
- Well for electronic geeks and for software personnel who would like to get into hardware programming, you can use the GPIOs (hardware pins on the RPI) to connect some sensors/switches/LEDs/actuators and assemble an automation system like the ones here.
Hope that was a brief 'elaboration'..!!