So I had not seen K-19 previously. In the interests of an accurate reply, I forced myself to watch it (ok, I skimmed parts).
K-19 is quite frankly ridiculous garbage. Hunt for Red October takes a few liberties, but is overall generally realistic, you can tell they tried to be realistic, and the departures are reasonable and logical. K-19 is a dramatic crap fest set on a submarine. Ok, the interior fittings are generally appropriate for a Soviet boat, however pretty much everything else about the movie is garbage. Examples:
Bow planes do not change ship's angle - that's what stern planes are for, yet they never seem to exist.
Ship settles on depth with a significant down angle, then magically levels off. Again solely because the bow planes are moved.
The reactor 'book of emergency procedures' is stowed randomly in a locker is some room on the other end of the boat, and the watchstander isn't, not to mention the reactor control panel is a child's toy.
Command and control, operational procedures, pretty much everything submarine related is just plain wrong. Admittedly it doesn't supersede Crimson Tide as the worst submarine movie ever made, but it's a close runner up.
Keep in mind Hunt for Red October was written during the bold war, and the movie filmed right at the end. Public information about submarines at that time was essentially nonexistent. Given the amount of public info he had to work with, it's rather amazing the book is as realistic as it is. K-19 in contrast was after a decade of far greater public information on subs, and today we have even more.