Santiago claims that a man can be destroyed but not defeated. What is the difference. Elucidate

Santiago feels that his fighting spirit will prevail. Fighting on the high seas does not mean defeat. Santiago also draws a distinction relating to the end of the story. Santiago does defeat and destroy the fish but is he ultimately defeated?  

"But man is not made for defeat," he said. "A man can be destroyed but not defeated." I am sorry that I killed the fish though, he thought. Now the bad time is coming and I do not even have the harpoon.