What is differences between services and skills?

[jungwookim]

kernel can add services and import skills.

In the docs,

Skill - A domain-specific collection made available to the SK as a group of finely-tuned functions.

Services don't have domain but it has characteristics like chat, summarization, text completion and etc. I think it should accompany a bit context and domain. Could you make the definitions clear? And is there any relations between skills and services?