@G8HAV 

One is a way of reserving an IP address, the other a security feature. 

 Reserve LAN IP   -  basically enter a MAC address of something, say a printer.  each time this device connects it will be given this address.  No-one else can be given this address via DHCP.     However... if I had a device that statically set that same IP address (not using DHCP) I could cause a conflict with the printer on the network as the DHCP would try to allocate that address which is already in use..

IP to MAC binding in short is a method to attempt to stop this.    Taking the example above, if I want to fix that conflict I can "bind" that MAC address to that IP.    This is nothing to do with giving the address out, rather which one to trust as legit.   In a conflict scenario it will choose the one with a binding.. if neither has a binding it will conflict.    In 20 years of installing servers, never had to use IP to MAC binding, but it is there.