eth0 和 en0 有什么关系？

在我的/etc/sysconfig/network-scripts/下面有ifcfg-en0和ifcfg-eth0:

[root@localhost /]# ls /etc/sysconfig/network-scripts/
ifcfg-en0    ifdown-ipv6    ifup          ifup-plip    ifup-wireless
ifcfg-eth0   ifdown-isdn    ifup-aliases  ifup-plusb   init.ipv6-global
ifcfg-lo     ifdown-post    ifup-bnep     ifup-post    net.hotplug
ifdown       ifdown-ppp     ifup-eth      ifup-ppp     network-functions
ifdown-bnep  ifdown-routes  ifup-ippp     ifup-routes  network-functions-ipv6
ifdown-eth   ifdown-sit     ifup-ipv6     ifup-sit
ifdown-ippp  ifdown-tunnel  ifup-isdn     ifup-tunnel

想问下en0和eth0有什么关系？