One cannot...
One cannot, however, see any difference between the two in the Holy Quran: But My Mercy extendeth to all things. [Holy Quran: A'raf 7:156] It is noteworthy that this divine attribute can be realized in the creation of all creatures, in provisions for their sustenance and their security against catastrophes. Man's supplication, using these two attributes, results in a mystic state and an especial spirit and joy. This will in turn result in God's attention and favor to his servant.
It has been noted in the Islamic literature that God said: I am ashamed of not responding positively to man's request should he invoke me through my Mercifulness and Beneficence. The creation of people and providing for their sustenance is the realization of His Mercifulness, and their guidance and prosperity is the product of His Beneficence.
God has commended His Mercifulness in other forms in the Glorious Quran in phrases such as "the Best of the mercifuls", "the Most Merciful of the mercifuls" and "Possessing Mercy." Even though figures cannot be used to express God's Mercifulness, the Prophet (Pbuh) has tangibly explained the matter to help people understand it: There exist one hundred of God's Mercies. God distributed one of these over the seven Heavens and the Earth.
He grants all people whatever they deserve with just that one mercy; and the people are loving and merciful to each other with what they gain from that one mercy. He has kept the other ninety-nine with Him so that on the Day of Judgment He add them to that one and distribute them amongst the obedient believers. Sovereignty implies ownership since God's Ownership spans over all creatures and worlds and is irrevocable.
He is an Owner who has full power over the growth and development of all creatures. The connection between His Ownership and plans for all existing particles is real, eternal and intrinsic. Therefore, it is not reasonable for man to choose another Lord or Owner, or accept any plans or laws other than His. Real monotheism can be really demonstrated in all aspects of life if man wholeheartedly submits to His Ownership and Plans and rejects any other ownership or claims thereof.
He must reject any culture or school of thought which oppressively intends to grasp a hold on man's life. The delightful phrase "There is no God but God" carries exactly the same meaning in all aspects of life.