Each person in the FamilySearch Family Tree has an assigned person ID. Learn how person ID numbers can help you with your family history.
Read the full story here
My husband has a different Family Search ID (shown in Family Tree App) than the one I have in my Family Tree. When I do a search for that ID number it shows "No Results"...???
Correct. Each person will having a different ID for any living person they add to the Tree. Please see this Help Center article: How does Family Tree protect the privacy of living people?