Determination and Tenacity are very close synonyms but it may differ when it comes to 'severity', because tenacity can also mean being stubborn or not letting go. read more
Tenacious means "holding tightly and not letting go.". It's more descriptive and therefore more specific. It says something about the character of the behavior in question. Determined means "resolute, or firmly decided.". It's more general, and it describes a mindset, rather than a behavior. read more
As adjectives the difference between tenacious and determined is that tenacious is clinging to an object or surface; adhesive while determined is decided; resolute, possessing much determination. read more
There is a big difference between bring tenacious and being stubborn. In both the cases you are exerting energy. In being tenacious, the source of the energy, the inspiration lies on the goal. You are tenacious because you want to achieve something. In being stubborn, the source of the energy, the inspiration lies on you. Not the goal. read more