Nmap Idle Scan and Spoof IP Difference

Hi guys,

I would like to ask what is the difference between nmap idle scan and spoof IP.

Assuming I have identified a zombie host as 192.168.100.1,

and my target as 192.168.100.2,

What is the difference in executing both commands as below:

Spoof IP: nmap -e eth1 -Pn -S 192.168.100.1 192.168.100.2

Idle scan: nmap -Pn -sI 192.168.100.1 192.168.100.2

Thanks.