While there are many comparisons between Bloom’s Taxonomy and DoK, the fundamental difference is that Bloom’s focuses on the type of thinking (the verb) - what is needed to complete a task whereas Webb’s DoK focuses on what follows the verb and the context in which it is applied. That is, how deeply you have to understand the content to successfully interact with it.
Furthermore, DoK is not about difficulty but complexity. Unlike Bloom’s Taxonomy, DoK levels are not sequential. Students need not fully master content with level 1 tasks before doing level 2 tasks. In fact, giving students an intriguing level 3 task can provide context and motivation for engaging in the more routine learning at levels 1 and 2.
The benefit of DoK is the focus on depth of understanding which can be assessed by reviewing student’s work and engaging in discussions with them. Also, the nonlinear nature means each level of knowledge can be chosen and purposefully planned for to achieve a desired outcome.