遍历list，判断list里面的项是不是TextRange，如果是，把它强制转换为TextRange，然后通过TextRange.Text属性获取差异.

using Spire.Doc;
using Spire.Doc.Fields;
using System;

namespace GetDifferencesInList
{
    class Program
    {
        static void Main(string[] args)
        {
            //Load one Word document
            Document doc1 = new Document("C:\\Users\\Administrator\\Desktop\\original.docx");

            //Load the other Word document
            Document doc2 = new Document("C:\\Users\\Administrator\\Desktop\\revised.docx");

            //Compare the two Word documents
            doc1.Compare(doc2, "Author");

            //Get the revisions
            DifferRevisions differRevisions = new DifferRevisions(doc1);

            //Return the insertion revisions in a list
            var insetRevisionsList = differRevisions.InsertRevisions;

            //Return the deletion revisions in a list
            var deletRevisionsList = differRevisions.DeleteRevisions;

            //Create two int variables
            int m = 0;
            int n = 0;

            //Loop through the insertion revision list 
            for (int i = 0; i < insetRevisionsList.Count; i++)
            {
                if (insetRevisionsList[i] is TextRange)
                {
                    m += 1;
                    //Get the specific revision and get its content
                    TextRange textRange = insetRevisionsList[i] as TextRange;
                    Console.WriteLine("Insertion #" + m + ":" + textRange.Text);
                }
            }
            Console.WriteLine("=====================");

            //Loop through the deletion revision list 
            for (int i = 0; i < deletRevisionsList.Count; i++)
            {
                if (deletRevisionsList[i] is TextRange)
                {
                    n += 1;
                    //Get the specific revision and get its content
                    TextRange textRange = deletRevisionsList[i] as TextRange;
                    Console.WriteLine("Deletion #" + n + ":" + textRange.Text);
                }
            }
            Console.ReadKey();
        }
    }
}