On field detail page, there are two different buttons called **Set Field-Level Security** and **View Field Accessibility**. What is the exact difference in them.
['https://salesforce.stackexchange.com/questions/208685', 'https://salesforce.stackexchange.com', 'https://salesforce.stackexchange.com/users/24950/']
From field level security you can define field visibility and read only for each profile

In field accessibility shows if a field is required, editable etc based on field level security and page layout configuration
In short, as @annappa has said, from field level security you can define field visibility and read only for each profile, 
while field accessibility show us if a field is required, editable, etc based on field level security and page layout configuration.

Also, I found a link that tells you in detail> [Newbie Q: Is "Field Level Security" the same as "Field Accessibility"?](https://salesforce.stackexchange.com/questions/131965/newbie-q-is-field-level-security-the-same-as-field-accessibility)

Hope this clarifies!