Although both terms imply “ justice ”, yet there is a slight difference in their meanings :
In a transaction between 2 parties (e.g. Buying and selling), to accord to both parties their due rights whence both are satisfied (win-win) – the Arabic term . ( QISTw ) is used. This may require willingness on one or both party to show benevolence, goodwill and generosity to the other.
To have Adab is (inter alia), to be taught not to forget what is appropriate and what is not in our perception and attitude towards others, and the ability to act appropriately with justice ( ‘ADL ) and goodness ( IHSAN ).
Thus Adab is not mere possession of ‘ knowledge ’. To be lacking knowledge is “ ignorance ”, but to lack Adab is “ ignorance compounded with conceit ”
“ These false leaders then usurped Islamic leadership, who (then) perpetuate the condition in (A)  above and ensure the continued control of the affairs of the Community by leaders like them who dominate in all fields.” 
[ 1] The loss of Adab in the community. Thus restoration of Adab has higher priority for Adab precedes even learning.
 Wan Mohd Nor Wan Daud’s “The Educational Philosophy and Practice of Syed Muhammad Naquib Al-Attas” (ISTAC publication 1998) p 74
Ta’lim ( ( generally it means, “ to teach ” or “ the teaching ” of knowledge as different from information, but a profound understanding of this word requires us to know the root word “ ‘ ilm” which is different from “ ma’lumat ”
Tarbiyyah ( ) – although used by many Islamist to refer to education (perhaps influenced by the Western methodology), it’s use to refer to ‘education’ is not appropriate due to its narrow and limited scope when applied to the Islamic approach to education, because our Islamic worldview regarding man is unlike those from the Western outlook that still regards man as an animal specie (although evolved).
Thus,“ Adab ” in the original basic sense (in Arabic) is the “ inviting to a banquet. ”
The idea of a banquet implies the host is a man of honour and prestige, and that many people are present; that the people who are present are those who in the host’s estimation are deserving of the honour of the invitation, and they are therefore people of refined qualities and upbringing who are expected to behave as befits their station, in speech, conduct and etiquette.” 
 S.M.Naquib Al-Attas “Islam and Secularism” page 149 TASAWWUR ISLAM BASIS