what is the difference bewtteen is_global_zero and rank_zero

[Maybewuss]

# code1
if self.trainer.is_global_zero:
    self.log(loss, sync_dist=True, rank_zero_only=True)

# code2
self.log(loss, sync_dist=True, rank_zero_only=True)

# code3
self.log(loss, sync_dist=True, rank_zero_only=False)

What is the difference between the above three usages？