Which type of sniffing technique is generally referred as MiTM attack?

Password Sniffing describes the goal or outcome of intercepting credentials from captured traffic - it is not a positioning technique and does not by itself place an attacker between two hosts.

ARP Poisoning works by broadcasting forged ARP reply packets that map the attacker's MAC address to a legitimate host's IP address, causing victim devices to send traffic to the attacker instead of the intended destination. This positions the attacker transparently between two communicating hosts - the core definition of a Man-in-the-Middle attack. Once in position, the attacker can capture, read, modify, or forward packets without either party being aware.

MAC Flooding overwhelms a switch's Content Addressable Memory table to force broadcast behavior, which can expose traffic but does not surgically position the attacker in-path between two specific communicating hosts.

DHCP Sniffing or DHCP spoofing can be used to redirect traffic by assigning a rogue gateway, but it is a distinct attack vector and is not the technique most commonly labeled as the canonical MiTM method.