The difference between gain phi and gain theta in hfss

Hello, I have two antenna and i would like to visualize the gain of this antenna, so i m find that in HFSS, it have two curves: the gain phi and gain theta in hfss, Can someone explain me the difference betwenn the two angles
Thanks in advance

E-plane corresponds to φ = 0°
& H-plane corresponds to φ = 90°

Each axis in 3D has an angle. To plot, one sweeps one angle while incrementing the other at 90 deg.
This assumes one axis is symmetrical.

thanks for your kind response,
I have three cases and I would like to do the comaparaison between the three case by studying the antenna gain so in your opinion it is intersting to visulaize the gain in abs or in dB ; in 2D or in 3D?
Thanks in advance