While assimilation deals with keeping existing knowledge and schemas intact and finding a new place to store information, accommodation involves actually changing one’s existing knowledge of a topic (Tan et al., 2017). Biological assimilation, according to Piaget, cannot exist without accommodation.

Assimilation: Attempting to interpret new information within the framework of existing knowledge Accommodation: Making small changes to that knowledge in order to cope with things that don't fit those existing frameworks

Here’s the difference: Assimilation: Improving existing knowledge of something thanks to new but congruent information. Accommodation: Amending existing knowledge of something thanks to new information that contradicts previous thinking.