Is the religious ruling on plunder the same as that on theft? Is plunder forbidden?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Both theft and plunder are forbidden. According to Sharee'ah terminology, a thief is a person who takes someone else's property stealthily from the place where it is usually kept and knows for certain that it does not belong to him or to someone whom he may lawfully take it from. On the other hand, a plunderer is someone who publicly seizes property, depending on power and dominance. Al-Buhooti said: "Once you realize that theft consists of secretly stealing someone else's property, (you will understand) in that case  that the plunderer 's hand is not to be cut off. The plunderer, here, refers to someone who takes other's property as a form of gain. This is based on the hadith that was reported by Jabir in which the Prophet, sallallaahu ‘alayhi wa sallam, said: "Cutting of the hand is not to be inflicted on one who plunders..." [Abu Daawood: Marfoo‘; Kashshaf Al-Qina‘]

Moreover, the Prophet, sallallaahu ‘alayhi wa sallam, warned against plunder, as Abu Hurayrah reported that the Prophet, sallallaahu ‘alayhi wa sallam, said: "No plunderer who plunders a valuable thing that attracts the attention of people is a believer so long as he commits this act." [Al-Bukhari and Muslim] 

Al-Haafith said, "The hadith refers to plunder in the sense of  publicly seizing another person's property by force." [Fat-h Al-Bari]

Allaah Knows best.