Does a zener diode gives better load regulation than line regulation or it depends?

Line regulation defines as the output voltage of the zener to remain constant under input line variation. Load regulations defined as the load increases or decreases the zener will control this variation by keeping the voltage constant....

i think it depends upon application..

I'm tempted to say, neither. But with small Vin to Vout voltage drop, line regulation will be worse. Just consider, how the Z-diode current changes in each case.

So, it gives better load regulation? is that it?

As said, the change in zener diode current is the cause of output voltage changes. If the load current is small related to zener diode current, load regulation will be better. But it's easy to calculate it for your intended circuit.