American English grades closeness with care, from a name in a contact list to a best friend.
We’re friendly. We get along well, but we are not friends.
We’re not close. We know each other, but we share little that is personal.
We know each other professionally. We know each other only through work.
An acquaintance. Someone you know by name and face.
A contact. A connection. Someone in your professional network.
A friend of a friend. Someone you know through a person you both know.
A close friend. A good friend. A real friend, not just a friendly contact.
A fair-weather friend. Someone who is friendly only while things go well.