How to check if a list contains htmlnode?

I am making a program that actively searches for content addition to a site and then write out to the console information about the content. I have an HtmlNode List containing all new content and another HtmlNode List containing all old content. My goal is to compare the two lists and extract the new content.

My code currently looks like this:

foreach (HtmlNode content in newContent){
     if (oldContent.Contains(content)){
          difference.Add(content);
}

My guess on why this does not work is because I retrieve the nodes in a new search. Is there a way of doing it other than having to compare the content of the node itself?

Thank you for any help in advance and happy coding.