I have a question on difference between use of "or" and "and". For e.g. what will be the difference in meaning of the below sentences and which one will be correct? The only difference between them is that first one is using "or" and the second one is using "and".

Natural foods do not contain color or flavor additives, chemical preservatives, or anything that has been synthesized

Natural foods do not contain color or flavor additives, chemical preservatives, and anything that has been synthesized

Pls can you help me understand the concept ? Thanks

In this case it's a list of things so And is the right usage.

And means both and or means either one of them
X and Y means both X and Y
X or Y means either X or Y

well, in contravention of what at least one poster has written above, or is almost certainly the best choice here; it depends on exactly what you're trying to say.

doesn't contain X, Y, or Z --> this means that none of X, Y, Z is present
doesn't contain X, Y, and Z --> this means only that not all three are present (i.e., at least one of X, Y, Z is absent).

i'm pretty sure the former is the desired meaning here, so you need 'or'.