Final answer:
The main difference is that Violetta Thurstan was a direct witness to a foreign invasion during WWI, whereas Fanny Kemble Johnson was not.
Step-by-step explanation:
The difference between the authors of "The Strange-Looking Man" and Field Hospital and Flying Column in the context of World War I is that only Violetta Thurstan was a direct witness to a foreign invasion during World War I. Fanny Kemble Johnson, while also an author during that era, did not serve in such a direct capacity.
This distinction highlights the different perspectives from which these women wrote about the war, which is a testament to the diverse array of experiences and reflections on the conflict that collectively contribute to our understanding of World War I.