As far as I know, coverage area is a very generic term and it can be used to say about cell coverage, network coverage etc. But tracking area is a LTE specific term and it is mainly used to manage paging procedure for ECM-IDLE UEs. When an UE is connected to eNodeB, its location is identified at cell level. Size of tracking area (# of cells within tracking area) . A very large or small sized tracking area can not be good fit in the context of network resource utilization. If tracking area size is very large then more # of cells shall be considered while paging idle users and in case of small size, frequency of tracking area update (TAU) shall increase which is signaling overhead as well as not good for UE's battery.
