When the Dura-Ace 12 speed groupset was launched, the Ultegra 12 speed groupset was also launched at the same time. This provided components at two different price points to suit different segments of the market. Dura-Ace for the pros and very serious enthusiasts, and Ultegra for the standard enthusiasts that don't want to spend so much for top performance.
Similarly for the new C50 wheelset, it is also available in Dura-Ace and Ultegra grades. I already have the Dura-Ace C50 wheelset and also the Dura-Ace C36 wheelset, installed on the Specialized Aethos and Focus Paralane respectively.
The Ultegra C50 is claimed to offer similar aerodynamic performance as the Dura-Ace C50, but with a lower price, at the expense of additional weight. This Ultegra C50 wheelset will be installed on the Giant TCR Advanced Disc 2 Pro Compact, as a good upgrade to the stock aluminium wheelset.
Ultegra C50 wheelset looks super plain, as the decals are grey in colour against the black rims.
I think the Ultegra logo is purposely made to be less obvious than the Dura-Ace, so as not to outshine it.