@rokkan if you do feel that implementing them on separate tables is what you prefer, do that. You can have the User model (that uses 'users' table) contain a 'userable' polymorphic relation id and type - this points to either an underlying customer profile or admin profile. If you don't think you'll have many roles (say no more than a 'customer' and an 'admin') then this might be the best way for you.

Recommended video: https://www.youtube.com/watch?v=5DVDewOReoY then the follow up to that: http://adamwathan.me/2015/09/03/pushing-polymorphism-to-the-database/

You should also check out http://laravel.com/docs/5.1/eloquent-relationships#polymorphic-relations

It is quite an advanced topic, and on top of that an unusual use case of polymorphism but it definitely lends itself to it - I have used it to mask customer types in a system I am building.