If it wasn't obvious, dv6700 is series and the other one is the exact model. Manufacturers tinker around with specs of a laptop series and make it available in different SKU models (for retail market, different countries, other such reasons).
You may have noticed in countries like the U.S., HP offers Built To Order services where you can configure the laptop according to your needs online and then the unit is built. In that case, you'd say that dv6700 series was customized for your needs.
I hope that made sense. In most cases, model numbers (dv67XXtu) give hint to their parent series (dv6700) as the case may be for identification/troubleshooting. And obviously, same laptop models will share same specs to avoid confusion.