HDR10 is the crap Samsung invented, which just extends 8-bit colour to 10-bit colour (from 256 shades of intensity to 1024). This is
not enough to display smooth gradients when going from the blackest blacks to the brightest whites that a high-dynamic range (HDR) screen is capable of. Hence, it causes visible banding, especially in "blue skies" or similar smooth areas of slowly changing colour.
Samsung worked around this by applying a post-processing filter that smooths out the banding... sometimes. It also almost always smooths away fine detail, ruining the 4K details. (Similarly, their 8K screens appear less detailed than some 4K screens for other but equally silly reasons.)
Dolby Vision uses a more optimal allocation of signal "bits" to the spectrum of colours and intensities visible to the human eye. The ideal is that each colour and each shade would be perfectly evenly distributed, so that "512" would be exactly half as perceptually bright as "1024", etc... The Dolby Vision encoding does this very nearly perfectly, eliminating visible banding without having to hide them by smudging the decoded picture. This optimal colour-volume encoding also means that transforms like scaling or brightness changes don't introduce colour-shifts or relative brightness shifts.
If you've never seen a DV video taken with an iPhone Pro 13 displayed on its OLED, you just don't know what you're missing. Go to an Apple store and play with one for a few minutes.
But seriously, companies like Samsung like to shave 50 cents off their flagship products by not paying DV their licensing fees. They figure that cutting corners like this doesn't matter, because most customers have no taste in image quality anyway, and just want BRIGHTER! COLORS! and nothing else.
They're right.
You don't care, and you're happy to save 50c on a $10K television or a $1K mobile phone.