be not so much (something) as (something else)
To be more accurately regarded as (something else) than (something). The phrase is used to emphasize that the the thing being discussed is more aptly described as the adjective after "as" than the one before "as," even if the first descriptor is also accurate. I'm so sick of this project. It's not so much difficult as it is boring.
be not so much something as something
be one thing but also something else which is more important: He’s not so much unintelligent as uninterested in schoolwork.