Here is a good read on the comparison of the two HDR formats: http://www.hdtvtest.co.uk/news/dolby-hdr-201606214303.htm

What is a bit misleading is it shows that Dolby Vision uses a much higher peak brightness (1000-10000 nits!!! (that burning in your eyes will never go away)) than HDR10 (540-4000 nits), but they had to lobby the UHD Alliance to accept that as a trade-off for the fact that Dolby Vision has much poorer black levels, 0.05 nits, whereas HDR10 reaches 0.0005 nits.

So DV may go much much brighter, its articulation of dark regions should be worse.