There's a difference between internal and external SATA (vs. eSATA) cables - the external cables are shielded and together with the slightly boosted voltages this relaxes the length restriction.
If you compare two internal cables, they *should* both perform equivalently. But if one is obviously flimsier that the other then it may not be as robust. I personally like my cables to at least *look* like they'll hold up under duress.