load_balance

LVS (Linux Virtual Server) will dynamically adjust its load distribution weights according to the latency distribution measured on each of the node.
Hot Standby Redundancy Protocol (HSRP) provide continuous availability of the cluster Virtual IP address (VIPA)
VRRP

Failover cluster

only one server gets the "virtual" IP address and handles incoming requests; if it fails, the other one becomes active in its place; there is only one web site active, so it needs no special tweak to run this way (but you should take care to onyl have data in locations accessible by all nodes); this setup is usually achieved at the O.S. level.

Load balancing cluster

both servers share a single "virtual" IP address and handle requests; the web site needs to be designed to handle multiple simultaneous instances (no local content on servers, proper session management, etc.); this can be achieved at the O.S. level or using a dedicated hardware load balancer in front of the web servers.

Virtual IP Address (VIPA)

only one virtual IP address will active, others will be standby.

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