In reply to wolfbane:
K2 is 520 metres, or 1750 feet, higher than Annapurna which does contribute towards making it more difficult to climb, especially in Winter.
Interestingly, as you mentioned, Annapurna has a lower number of successful summit attempts and a higher death rate measured as a percentage of ascents. In fact Annapurna has the highest percentage death rate of all the 8000 metre peaks.
Its worth having a look at the Alan Annette web page which gives a lot more detail.
https://www.alanarnette.com/climbs/8000ers.php
Post edited at 21:31