Simple appositive: 1. The witch, Helga, ate my dog.
Restrictive appositive: 2. My cousin Helga is the witch.
(In the second sentence Helga specifies which cousin.)
Simple appositive: 1. My wife, Cherry, left me.
Restrictive app: 2. My wife Cherry left me.
(The second sentence would be okay only if I had more than one wife, and the name specified which wife left. Whew! I thought she’d never get out.)
Simple Appositive: 1. My son, Luke, is in the Navy.
Restrictive App: 2. My son Luke is in the Navy.
(Again, the second sentence is only appropriate if I have more than one son.)
Simple Appositive: 1. My youngest son, Luke, is in the Navy.
(By adding the word youngest, I have already specified which son, even if I have many sons. Luke reverts back to a simple appositive.)