Are Immage Stabalization and Vibration Reduction are same or they are different terms?

Are Immage Stabalization and Vibration Reduction are same or they are different terms?

Different names for the same thing - Sigma call it Optical Stabilisation (OS).

Sony and Pentax don't bother with it as their stabilisation systems are built into the camera body.

Yes, they are different names for the same thing

Same thing, different terms. They're both anti-shake technology. Canon and Nikon implemented theirs on the lens allowing for more calibrated anti-motion compensation. Pentax and Sony did it on the body which effectively allows the technology to work with all lenses including decades-old ones that were made during a time when digital wasn't even conceptualized yet.