I am learning about SAN. I know about LAN and NIC. I wanted to what is the difference as per the above subject of the question? HBA/CNA supports Fibre Optic Cables (SMF/MMF). Please provide some specifics, that would be much appreciated.
To understand the terms you have to understand some history.
A "host bus adaptor" was originally something used to connect a SCSI storage bus to a host computer. You could in theory have multiple computers on the same SCSI bus but limits on total devices made it impractical to have more than a couple.
The networking world used the term "Network Interface card" or "network interface controller" (both abbreviated to "NIC") for the device used to connect a computer to a network.
Systems like Fibre Channel that were primarily used for storage kept the name "host bus adaptor" even as the storage network grew way beyond a simple bus.
People started wanting to build storage networks based on Ethernet because Ethernet is a lot cheaper than dedicated storage networking technologies and because it's often useful to only have to run one infrastructure rather than two. Various technologies have been created for this including "Fiber Channel over Ethernet".
To support this at a hardware level device vendors introduced new "converged network adapters". These provide support for both regular Ethernet services and hardware support for storage-specific protocols. For example Intel's cards support both Fibre Channel over Ethernet and iSCSI.