0.3 vs 1.3 Mpix webcam

I want to know the difference between these cameras on the laptop, when it comes to video call. For example, Video call via Skype. with this 2 cameras. I want to buy laptop with webcam that has good quality of video, and many of good laptops that I found have 0,3 Mpix. But I watched video call on 1,3 Mpix webcam at my friend's laptop...and It looks like 0,3 Mpix.
I read somewhere that these cameras are (in most cases) the same, when it comes to video call...that this resolution difference is in taking pictures.

Can someone explain this to me a little better? How can I know what is the quality of the viedeo call on some laptop that I want to buy?

 

That is because of something called CoDex. Compression / Decompression schemes that 'squeeze' the video down so all your bandwidth is not used up, allowing you the talk, move, & type all at the same time without being to laggy.
Usually software chooses the codec so you can't pick other than 'quality' or resolution some times.