A genus-differentia definition is one in which a word or concept that indicates a species -- a specific type of item, not necessarily a biological category -- is described first by a broader category, the genus, then distinguished from other items in that category by differentia. The differentiae of a species are the species' properties that other members of the genus do not have. In short, the genus is the broad category, the species is a type within that category, and the differentiae are the distinguishing characteristics of the species. This is a type of intensional definition.
Under the "genus" and "species" description, this sort of definition is used to categorize different plants, animals and other things into biological categories. See also genus and species and Linnaean taxonomy.
This can be clarified with a hackneyed example. Suppose we wanted to define the phrase human being. Following the ancient Greeks (Socrates and his successors) and modern biologists, we say that human beings are members of a species. So we ask what the genus, or general category, of the species is; the Greeks (but not the biologists) would say that the genus is animal. The genus, then, is animal and the species is human being. What are the differentia of the species, that is, the distinguishing characteristics, that is, the properties that human beings have, that other animals do not have? The Greeks said it is rationality: the things that humans have that other animals do not is rationality. So rationality is the differentia of the human species, according to the ancient Greeks; thus Aristotle said, "Man is the rational animal." [1] By this he meant to be giving a definition of "man," or of "human being."
However, the use of the genus-differentia definition is by no means restricted to science. Rather, it is the natural thing to do if you are to explain the meaning of a particular word to someone. With this, the "classical" type of definition (Definitio fit per genus proximum et differentiam specificam.), you use the copula (is, are) after the definiendum (just as if you were using an equals sign in a mathematical equation) and then go on to explain the definiendum by using the appropriate generic term plus those characteristics specific to the thing you are describing which consecutively narrow down the meaning until the definiendum can no longer be confused with anything else.
from Wikipedia
For Jehovah's Witnesses the "Jehovah" is a Brand in much the same way Coca Cola or Honda are brands.
If JW's were monotheists such a distinction would be redundant. But, monotheism isn't part of JW theology because Jesus has the status of "a god". (NWT rendering of John 1:1)
Consequently, JW's are forced to distinguish Jesus FROM Jehovah and distinguish themselves from christians for whom CHRIST is the essential brandname (CHRISTian).
The theology of Jehovah's Witnesses centers around the religion itself and not God in a Narcissistic self-importance quite beyond the pale.
Whatever role Jesus has in JW theology is a prop for the activity of the human servant of the Watchtower Society which has branded them Jehovah's Witness and not Jesus' Witness or Christ's Witness.
The purpose of the door to door activity is to create a category of publicity for the Watchtower because of the magazines distributed (Watchtower) that no longer announce the advent of Jesus Christ in deference to Jehovah's Kingdom.
This mugging-for-the-camera aspect of Watchtower mania for contrarian publicity has resulted in many destructive and wrong-headed stunts demanded of the rank and file worshipper at the local Kingdom Halls which include:
1.Not celebrating holidays when everybody else who is Christian does celebrate.
2.Not saluting the flag, voting in elections or volunteering for community work for charity because everybody else who is Christian does.
3.Not calling their meeting place a church because everybody else who is Christian does.
4.Not espousing theology mainstream Christianity espouses or representing the sacrifice of Jesus as a death on the Cross because everybody else who is Christian does.
The list is practically endless!
The object and manner of Jesus' return was the essential feature of early Bible Student curiousity and preaching activity. It was a Christian activity. Yet, soon after, the lure of connectedness with the personality of Pastor Russell and his Studies in the Scripture changed their direction to End Times Date Setting and a cult of personality (Russellites) channelling the Spirit of God through the ad hoc doctrine of Maria Russell (faithful and wise servant).
Today, no longer Christian and no longer Russellite, Jehovah's Witnesses are a Brand name religion wielded by carnival barkers, hucksters and salesmen at Conventions, door to door and at Kingdom Halls for the enrichment of the Brooklyn investment portfolio.
You won't find Jesus here. You'll find a lackluster CEO Kingdom already established in 1914 which hasn't lifted a finger in 93 years to bring about world peace or usher in paradise or heaven for anybody!
The JW version of Jesus is a ne'er do well who keeps his butt on the throne ruling over his faithful flock as they endlessly spout News Flashes about the deal He is going to close--but--never getting the time and place of the meeting correct!! As secretary to the boss the Faithful and Discreet Slave don't take dictation very well at all!
This "Jehovah" holds the heart and imagination of Kingdom Hall publishers and Jesus is a mere inconvenient afterthought.
They aren't Christian at all.