/etc/sysconfig/network typically contains general information about networking on the system. Should interfaces even be activated? Which ones? What is the primary interface? What is this system's name and identity?
The other file you mention,
/etc/sysconfig/network-scripts/ifcfg-eth0 is specific to the first ethernet interface, known in the linux world as eth0, and has details about whether to use DHCP or assign an IP address, whether THAT interface should be activated on boot, and so on. You will find one of these files for each interface on the system. Laptops for example often have
wlan0 as a wireless ethernet devices, and many systems with multiple network cards will keep going with