Difference between Form level security Vs Field level security?

 Form level Security:- Form level security used to secure a form, using this form level security we can restrict the Entity form to displaying for everyone OR Displaying only for some security roles.

Field level Security:- Field level security in CRM lets you dictate which fields users can view or edit. If you want to prevent users from (accidentally) changing data like an account name, account number or status, enabling or disabling field security for a field can give them read only access to these specific fields.