It's 'hike'-vision, as they say in this video. Related, Dahua's pronunciation video.
Hikvision probably OEMs to a hundred plus different companies, so the only people who would definitely know what is shipped to all the OEMs are very senior people in Hikvision.
That said, the safest / fairest statements are (1) Hikvision has a far broader product portfolio than any of their OEMs and (2) the OEMs tend to focus on more basic products. For example, Hikvision sells 2 series, 4 series, 6 series. They also have a 1 series, the lowest end, which they do not directly / branded sell in North America but is OEMed.
So, at some level, I think they do sell 'inferior' good but by design and with agreement to their OEMs, like ADI, who wants cheap, bare bones products.
I use both Hik and their OEM products almost interchangeably depending on who gives me the better pricing or the availability depending on our need.
The Hikvision cameras come with mounting brackets for octagon boxes - this is a big deal for us for new installs as we prefer to mount cameras onto electrical boxes. Other than that, the camera, DVR and NVR firmware are updated in different intervals, but everything still works nicely together.
Warranty from where I get the OEM equipment is 5 years and my gold status with Hikvision also gets me 5 years. I have yet to have any equipment fail on me prematurely.