Nonetheless vs. Nevertheless
I hope that you're as interested in learning about confusing grammatical structures as you are in learning about semantically confusing words. C'mon.
What Is Their Main Difference?
Both are conjunctive adverbs indicating two opposing and contrasting ideas. They both come between two clauses. Native speakers tend to use 'nevertheless' more than 'nonetheless' because the former sounds better.
Differences
These two are not different. The issue is that native speakers prefer 'nevertheless' to 'nonetheless'. Look at the examples below:
These two adverbs are totally the same;
Sonya woke up early;
Similarities
They are both conjunctive adverbs. They function like coordinating conjunctions in that they both connect two independent clauses. Note that the sentences are contrasting. Look at the following examples:
I spent all the party talking to her;
Our math exam was really difficult, but we managed to pass
Are They Interchangeable?
Native speakers often use these two terms interchangeably. Compare:
✓ I was prepared for my nursing test;
✓ I was prepared for my nursing test;