I was wondering what causes a difference between the left and right channel of a sample ? And is it bad or ok, depending of the type of the sample

 

Probably panning. Is the audio just one instrument playing? Then it's panned a bit to the right as shown in your image.
Are there multiple instruments playing? Then one or more sounds have been panned to the right.
Not bad at all and easy to correct if thats what u want. Try reducing the stereo width. Or use a balance panner. Or split the audio so you have two mono tracks, u can pan those however u like.

Or maybe the right channel is just louder then the left. Also not that hard to fix.

 

Last edited: May 16, 2017

In this case it's only 1 instrument. I didn't panned but maybe it's the mid/side side chain.

 

if you need to fix this fast, Izotope RX is a good choice. Go to the "Channel Tools" or whatever they are called. It will scan the sample, equalize the volume for you if that's what you want.

 

If it is a mid side problem you should be able to fix it with something like brainworx xl. Or any other eq, comp or limiter with mid side functions.
Could be the stereo (side) is louder then the mono (mid) or the other way around. In both cases reducing or increasing the stereo width will help.
By the way.....this is why prefer to work with mono files.
If and when i use stereo samples or loops i always check em with bx_digital.
Makes it easy cuz you can see if the side part is actually louder then the mid.
But if that is the case you should be able to hear it aswell.
Just place yourself in front of your speakers (sit in what is called the sweetspot) play the audio and close your eyes.
Where is the music coming from. Can u clearly hear it coming from one side or the middle.....
Does it seem to be played far away in the background or is it upclose.

I would recommend you try that before using any plug to correct it. And when in doubt make it mono.
U can always make it stereo later on with hundreds if not thousands of plugings from delays to chorus, phasers, reverbs and so on.