This article contains many indications of what information may be on the denim jean labels of authentic designer jeans.
Micro stitching on the labels; a particular font used on a certain brands label; serial numbers printed onto labels, rather than stitched; the number of labels attached (The more labels is a good clue of authenticity); Inside labels will have small close stitched threading.
All of these features, & more, may be indicative of having a genuine pair of designer jeans.
There are so many brands of denim jean that it would be difficult to tell which particular security or design feature is on them all. This article gives a starting point with many features which are present in some different manufacturers.
Read through the complete article, it will give indications & clues of what information would be on a genuine pair of designer label denim jeans, not just the labels.