Clustering and load balancing

Question

1. What is the difference between clustering and load balancing from SharePoint point of view?
2. When we say "high availability" does it mean clustering or load balancing or both?

Answer 1

Network Load Balancing is a type of clustering. It can be software or hardware based but if you are talking about SQL clustering which is used in SharePoint environment. Here's an example of how load balancing and SQL clustering works together,

"High Availablity" means both but "somehow" but depends on farm topology.

Check this MSDN article out for more detailed information.