Differences Between `/dev/null` and Devices Under `null_blk` Driver

I recently encountered the [Linux Null Block device driver](https://docs.kernel.org/block/null_blk.html) , null_blk, while I benchmarking the I/O stack instead of on a specific block device. I found the devices created under this driver (let's use the device name /dev/nullb0 as an example) quite intriguing, especially considering their similarity in name to the /dev/null device. Since I couldn't find any existing questions on this topic from Stackoverflow, I decided to reach out for clarification. My main question is: **what are the differences between the /dev/null and the block device created under the null_blk device driver?** --- To this point: I've already noticed some distinctions. - First, (as far as I understand), the null device /dev/null doesn't go through any driver. However, devices created under null_blk are true block drivers that the data must pass through. I also confirmed this by running fio on both devices; /dev/null performs much better in terms of random read IOPS and submission latency. - Second, we know that reading from /dev/null results in an EOF (for example, cat /dev/null), but when I attempt cat /dev/nullb0, it doesn't return an EOF and instead hangs. - Additionally, as a side note, the kernel documentation for null_blk mentions parameters for configuration, but I don't see any similar options for /dev/null to be configured. It seems, large number of differences exist under the similar names. Can someone provide further also formal insights or clarification on these differences? Thanks!