My advice would be to keep it consistent whatever you decide to use.

I prefer absolute URLs. That’s just a preference. Google will crawl either if the local setup is correctly developed.

• What is an absolute URL? Example – http://www.surjeetthakur/search-engine-optimisation/
• What is a relative URL? Example – /search-engine-optimisation.htm

Relative just means relative to the document the link is on.

Move that page to another site and it won’t work.

With an absolute URL, it would work.