The Country with the Most Islands

I've seen two strikingly different figures for the number of islands in Sweden. WorldAtlas and Wikipedia both agree with the question setter, saying that Sweden has 267,570 islands; but other websites (e.g. worlddata.info) put the figure at 221,831. All of these sites seem to agree on the figure for Norway: 239,057.

Either one or more of these sites is out of date, or they're using different criteria for defining what is and what isn't an island. And if we're going to be setting (or answering) questions like this, we need to know which it is. Because according to worlddata.info, the country with the most islands is Norway.

worlddata.info suggests that "In general, we speak of an island when it (sic) big enough that it can develop its own vegetation. For example, a tree or a bush." But then it appears to contradict itself: "The bare, steeply towering rocks in Scandinavia are also considered islands."

The consensus does seem to be that Sweden has the most islands, with worlddata.info being alone in favouring Norway. But until we know why the figures are different, this will remain a dodgy question for me.