Is there any difference between plain_text vs text.content?

[wongww]

{
  "Title": {
    "type": "title",
    "title": [
      {
        "text": {
          "content": "A better title for the page",
        },
        "plain_text": "This is also not done",
      }
    ]
  }
}

In the documentation, it shows that plaint_text and content are different values.
While using Notion's API, I have never seen plaint_text and content be different. So, what is the difference if there are any?