If the job is being quoted and sold as a Cat6 installation, then you won't have any issues using Cat6e. 6e is not an official standard, but something that the manufacturer dreamed up on their own to indicated that their cable exceeds the requirements for Cat6. It would be like calling their cable "Super Cat6" It really doesn't mean anything, it's just marketing. It may have a higher twist ratio, it may have better resistance to cross talk. In practical terms the network isn't going to know the difference, but it may be a bit more difficult to terminate.

You can look up the standards info for Cat6 and Cat6a, but for "6e" you would need to check the manufacturer's website for that specific product.