Bahmed -
Yes they are HA for each other and they are a cluster.
You create the cluster on the first node, then join the second to the cluster.
See the 'Software Setup Guide' and 'High Availability Configuration Guide' books in the ONTAP documentation:
https://mysupport.netapp.com/documentation/docweb/index.html?productID=62379&language=en-US
I hope this response has been helpful to you.
At your service,
Eugene E. Kashpureff, Sr.
Independent NetApp Consultant http://www.linkedin.com/in/eugenekashpureff
Senior NetApp Instructor, FastLane US http://www.fastlaneus.com/
(P.S. I appreciate 'kudos' on any helpful posts.)