This
Wikipedia article will give you a pretty good summary of where the name Jehovah comes from. It is an English corruption of the Hebrew name for God.
Who are Jehovah's witnesses?
They are a cult that sprung up around the teachings of a man, Charles Taze Russell, in the late 1800s. Of course, they would not consider themselves a cult, but true believers and everyone else that calls themselves Christians they would call apostates.
The following answer is lifted from their website:
Jehovah is the personal name of God, as found in the Bible. A witness is a person who relates facts from direct personal knowledge or proclaims views or truths of which he is convinced. Thus, the name Jehovah's Witnesses designates an organized group of Christians who proclaim the truth that Jehovah is a loving and just God, deserving of our love and obedience. They do this by sharing what they have learned from the Bible with friends and neighbors.—Isaiah 43:10-12.
According to them who is GOD?
Again from their website:
Jehovah is the name of the only true God, the Creator of all things. As such, he is worthy of our worship and devotion. His outstanding qualities are love, justice, wisdom, and power.—Psalm 83:18; 1 John 4:8; Revelation 4:11.
How r they different from other christians?
Well, while Jehovah's Witnesses would call themselves Christians, I woud not use that term to describe them. They have some things in common with Christians (but then so do Jews and Muslims), and they even use some of the same religious language that Christians do, but they often have different meanings for the terms and widely divergent interpretations of scripture from what Christians do. Some of those things, you, as a Muslim, may actually find yourself agreeing more with the Jehovah's Witnesses than historic Christianity, and that in and of itself ought to be a clue to you that they are not actually Christians.
Probably the first among those is that they reject the concept of the Trinity and the diety of Jesus. You can find a lot more about what they believe on
their website.
My great-grandfather was a Jehovah's Witness. I have all of his old books. One of the things the JWs are big about is an expectation of the imminent end of the world. My great-grandfather sold everything he own for that end which was supposed to occur in 1914. Somehow he lived through that event, which is now explained as being the date that Jesus Christ invisibily returned, so we are living during the "end of the world".
So the "end of the world" does not mean the end of this world in destruction. If it did there would be no need to raise up witnesses for the "end of the world"
The Bible term "end of the world" means, here, a new time period, the "time of the end" of this old world. This time period had its beginning in 1914; it will close when this world ends in destruction. So 1914 marked the beginning of the "time of the end" for this world.
From Paradise Lost to Paradise Regained, p. 174
However, my great-grandfather's older books and publications (pre-1914) say something completely different. According to them,
Suppose that A.D. 1915 should pass with the the world's affairs all serene and with evidence that the "very elect" had not be "changed" and without the restoration of natural Israel to favor under the New Covenant. (Rom. 11:12,15) What then? Would that not prove our chronology wrong? Yes, surely! And would that not prove a keep disappointment? Indeed it would! It would work irreparable wreck to the parallel dispensations and Israel's double, and to the Jubilee calculations, and to the prophecy of the 2300 days of Daniel.... What a blow that would be! One of the strings of our "harp" would be quite broken."
from The Watch Tower, October 1, 1907
Well, Russell was wrong when he said that such a happening would be irreparable. They repaired it quite nicely, setting a new date for 1925, which my great-grandfather also believed. They have since quit setting exact dates and thus began the teaching of the invisible coming of Christ in 1914.
And though they don't present themselves to people when knocking on doors today, they have in the past been quite antagonistic toward all other beliefs:
There is no such thing in existence as "the Christian religion," because
all religion [emphasis mine] proceeds from God's enemy the Devil. "Christian religion" is a misnomer, fraudulent and deceptive.... Religion is entirely out of place in the church of God.
J.F. Rutherford, Enemies, c. 1937, p. 130
I hope from the above statement by the then leader of the Jehovah's Witnesses you can see why I say that they have nothing in common with historic Christianity. They themselves have said that they don't want to be considered Christian. Though today, in the FAQ section of the website they answer the question, "Are you Christian?" with a "Yes". I guess times change. Though in 1945 they were still saying that " 'Religion' is the doing of anything that is contrary to Jehovah's will."
JWs claim that after God created the Son in heaven that then God became a father. The Son of God was put in the already conceived human embryo in Mary, but he was born a mere human creature, and the God begot him to be God's spiritual son once more, instead of a human son, at Jesus' baptism. Jesus did not die on a cross, but was executed by being impaled on a stake. God then removed Jesus' dead physical body from the tomb. Jesus was resurrected spiritually, not physically. And for the time that he was supposedly in the tomb he simply ceased to exist altogether. Since there is no bodily resurrection, there can be no physical second coming, which explains why people missed his invisible but spiritual return in 1914.
How are JWs different from Christians in their beliefs? It would be easier to tell you how they are alike. But I can't even tell you that both believe the other is going to hell, because JWs claim that those who are beyond redemption (like Christians and Muslims) simply cease to exist or to ever have existed and enter a state of complete annihilation of their being.