All of those words are synonyms, meaning they Have similar meanings, but they go about describing things differently.
Bewitched - "He was seemingly bewitched by her angelic voice." This implies he was captivated by her voice, or as though he were casted under a spell.
Spellbound - "The man's glowing green eyes kept the young girl spellbound." In this sentence, the word is used to describe how his eyes kept her entranced, or held her attention.
Enchanted - "The group felt enchanted by the graceful deer trotting in the meadow." Here, the sight of such a beautiful scene was very enchanting, or mesmerizing.
Fascinated - "My daughter was fascinated by my ability to tie a cherry stem with my tongue." Fascinated here means that the daughter was showing great interest to her mother's ability.
They sound very much alike, so I can see where it can be confusing.