difference between Theme.AppCompat, @style/Theme.AppCompat, and @android:style/Theme.AppCompat

Question

what's the difference between:

• Theme.AppCompat
• @style/Theme.AppCompat
• @android:style/Theme.AppCompat

and in which case should we use one vs the other?

Also, does it make a difference if we write

<style name="CustomActionBarTheme" parent="Theme.AppCompat">  

instead of

<style name="CustomActionBarTheme" parent="@style/Theme.AppCompat">