Library Connection LAN or SAN

My question is inquiring some information on Netbackup and Oracle Library SL500 

What's the difference between the backup over SAN and over LAN? I'm asking that question because I have a tape Library SL500 and the thing is that I know from Oracle side that the data is transferred to the library through SAN cables and there is no LAN connection with this tape library so I got confused in such case ? 

so can any one here help me with discussing this ? :)

Thanks in advance