Losing your job on a HSP visa means you need to find a new job in 3 months. For a regular work visa, there's no such requirement; you have until the visa expires, whenever that is (which could be less than 3 months, or much more). The regular work visa is also not tied to an employer (HSP is though).
It's not nearly as bad as the US. And yes, from what I've heard, renewal is pretty much guaranteed unless you badly fuck up somehow.
> For a regular work visa, there's no such requirement; you have until the visa expires
That's wrong. The same rules apply. After 3 months immigration can (but is not required to) force you to leave the country. Both for HSP and e.g. specialist visa types.
For a regular work visa the requirement to engage in activities appropriate to your status of residence can be covered by job seeking etc., whereas for HSP (i) there is no way to satisfy it except working for the specified employer.
It's not nearly as bad as the US. And yes, from what I've heard, renewal is pretty much guaranteed unless you badly fuck up somehow.