You're either realtime or you're not. If you have hard and fast time requirements to perform certain actions then you're real time. (e.g. 3 ms. to decide whether or not to turn the cruise missile or it hits a hospital). There is no 'soft' realtime.
There is soft realtime. You don't have to have hard and fast time requirements, or nothing, you can have more relaxed statistically defined requirements. That is soft realtime.
Systems are not divided into cruise missile control systems and everything else. There is a continuum in between. A phone system where the calls need to routed in the 100 milliseconds or less 99.999% of the time is acceptable for example, while one where no such guarantees can be provided at all is not acceptable. It is not a realtime systems but it is pretty close, so it would be called soft realtime.
