All new models are members of the Ultraforce lineup.
http://www.notebookcheck.net/Gigabyte-launches-new-P-series-gaming-laptops.144025.0.html
I honestly don't really understand why they are launching P series and AORUS brand at the same time. They both are high performance gaming laptop, but if P series is so much cheaper, and as strong as AORUS laptops.... why do they expect customers to buy AORUS instead of P series.
For the same reason that Dell keeps the Alienware brand on the market. Sometimes having gaming-capable specs is not enough.