What is different between kernel parameter and kernel modules?

Modules are code pieces that dynamically can be loaded into memory. Parameters are data passed to code inside the kernel (or modules).

Some parameters aren't related to modules. Go to kernel.org and look at how the kernel is organized. There's a tons of parameters in /proc and /sys to tune anything from networking to disk caching.

Parameters on the kernel line (that you see in /proc/cmdline) are mostly to manage the boot process, getting initial system stuff done, which could be in modules. And remember, modules can be compiled directly into the kernel too - they don't have to be dynamic.