Some of their beliefs are similar but not all. The Jehovahs Witnesses were founded by an ex Baptist by the name of Charles Taze Russell.
"The Jehovah's Witnesses tradition is a religion founded in the late 19th century C.E. in the United States. Founded by Charles Taze Russell, Jehovah's Witnesses grew out of
the Christian Millerite movement and has since spread worldwide. Jehovah's Witnesses doctrine is grounded in Russell's teaching that the Second Coming of Christ has already occurred (in a spiritual, invisible form) and the visible form that will follow will include the establishment of Christ's millennial kingdom here on earth. The group took on the name "Jehovah's Witnesses" in 1931 under the leadership of Joseph Franklin Rutherford."
The name refers to belief in the imminent Second Coming (or "Second Advent") of Jesus
Christ. William Miller started the Adventist
movement in the 1830s. His followers became known as
Millerites.
Adventism - Wikipedia