We have all heard of the well known Arab families, such as
آل سعود (Al Saud),
آل صباح (Al Sabah),
آل ثاني (Al Thani),
آل رشيد (Al Rasheed), etc. The word
آل came from either the
جذر أ و ل , which has to do with family or people, or from the word
أهل , from
جذر أ ه ل , which also has to do with family or people.
آل البيت could refer to the blood relatives and descendants of
محمد
أهل البيت could refer to all Muslims collectively or to the family of
محمد
Some Arab tribes have names like
آلبو صالح (Albu Salih) or
آلبو نمر (Albu Nimr). The
آلبو is a shortening of
آل أبو . So
آلبو نمر is really
آل أبو نمر , The Descendants of The Father of Nimr, or the Abu Nimr Tribe. But the people just say
آلبو نمر , and so we write Albu Nimr.