Ask HN: Difference between custom and template design?

I have been browsing lately a lot of designs and I see a pattern, custom websites (at least this is how they are called) seems to be using parts of popular templates, like CSS/Grid Systems. So a questions to HN community - what do you consider a custom website? Are you OK if the custom website is using parts of commercial templates? Where is a line between custom and template? Can a template that was vastly customised called custom?