The term "refuge" refers to a place or condition of safety and protection. A "shelter" refers to a physical structure that protects from weather or danger.
* The term, "city of refuge" in the Old Testament referred to certain cities where a person who accidentally killed someone could run to for protection from people who would attack them in revenge.
* Sometimes "shelter" means "protection" as when Lot said that his guests were "under the shelter" of his roof. He was saying that they should be safe because they were in his house.