Hard skills are skills that are easy to measure. For example, the score on a specific test, you can measure wither the person can do arithmetic's, algebra, spell words etc. This gives you hard evidence that the person possesses these skills.

Soft skills are skills that are hard to measure. This includes social skills, but also other things like being able to create a good architecture for a complex software project etc.

There is nothing stating that soft skills needs to be social and hard skills needs to be technical, if you mean those then just say social or technical instead of soft or hard.