What is the difference between CSFB and eCSFB?

Tg 170616a (Pakistan):
Can any1 tell me the difference between csfb n ecsfb??

CSFB: The UE release de eNodeB and redirect to the target CS domain and performs de CS Call Setup
eCSFB: UE performs the CS Call Setup while the still camp on LTE. After the UE is redirected to CS domain, starts the CS call.