The preprint papers on arXiv are like 99% the same as the published versions, except they're free instead of locked behind a multi-thousand dollar/year paywall.
And if there are differences, that is often a good thing! It can mean the author wanted to format something in a particular way that the journal didn't allow.
And if there are differences, that is often a good thing! It can mean the author wanted to format something in a particular way that the journal didn't allow.