According to: http://thesaurus.com/ Yes, WILL and DETERMINATION are synonymous. d:-D

As others have said, the two words are often synonymous. However, both have other meanings. For example, "the FAA has just announced its determination that pilot confusion was the major cause of the Asiana Airlines crash at SFO" and "the dying man made a revision to his last will and testament". That said, I also think that "determination" is a trait of one's personality and character. It is about one's ability to stick to a goal, especially in the face of obstacles. "Will" is something a bit deeper that has to do with the psyche and is even sometimes spiritual. To talk about someone's "will" is to talk not just about their persistence and determination; it is to talk about the importance of their most heartfelt goals and ambitions. In a life-or-death situation, we might talk about "the will to live".

As far as I understand, "Will" refers to mean "intention". While "Determination" means the extreme case of "will". In some case both of the word can express the same meaning. And you should use, "It is his strong will that made him succeed"

determination mean: a. The act of making or arriving at a decision. b. The decision reached. you can see that :) there are interesting articles :) http://www.kent.ac.uk/careers/sk/determination.htm