Based on the original post, i can only assume by the phrase 'starting on wort' that the actual batches were the same size, but the boil volume (or resulting wort) was different prior to adding water to reach that batch size.
Assuming this is right, here is how 'boil volume' can affect your beer:
1) too 'thick' a boil can result in, what i call, extract twinge. A weaird, chalky flavor common in homebrews. this is my opinion.
2) the thicker the boil, the less IBU's will be extracted from the hops (assuming boil time and qty of hops remain the same). conversely, the 'thinner' the boil, the more utilization from hops you will have. Trust me, a few yrs back I made a rookie mistake and decided to change my recipe on the fly. In order to limit the extract twinge, i decided to add half of my extract at flameout, although i wrote the recipe assuming all of it was added at the start of the boil. What was supposed to be a mildly hopped nut brown turned into one hell of a bitter beer!