It might be helpful to answer your question by providing some examples.
Let's assume you are afraid of spiders. These are some sentences you can use.
- I am afraid of spiders.
- I am scared of spiders.
- I fear spiders.
These all have a similar meaning. However the last sentence, "I fear spiders", is not generally used in English. Instead a more common sentence would be, "I have a fear of + object."
For example:
- I have a fear of spiders.
- I have a fear of heights.
- I have a fear of snakes.