Settings restricted to profiles versus permission set grants
Key Takeaway
The profile sets a user's defaults, and permission sets add access on top of it. A permission set can add a custom record type, but default record types and page layout assignments live only in the profile.
Profiles and permission sets both control what a user can do in Salesforce, but they do different jobs. A profile holds default settings, such as the default record type, page layout assignments and login restrictions. Permission sets add access on top of the profile, and Salesforce recommends them for object, field and user permissions.
How profiles and permission sets fit together
Profiles and permission sets can both hold user, object and field permissions and access settings. Every user is assigned exactly one profile and can also have many permission sets. So the profile works as the baseline, and permission sets stack on top of it.
Permissions control access to object records and tasks. Examples include viewing the Setup menu, permanently deleting records in the Recycle Bin and resetting a user's password. Access settings control other functions, such as Apex class access, app visibility and the hours when users can log in.