A Semite is someone descended from Shem, one of the sons of Noah. A Hebrew is someone descended from Heber, one of the great-grandsons of Shem. So all Hebrews are Semites, but not all Semites are Hebrews. Six generations after Heber, Abraham was born to his line, so Abraham was both a Hebrew and a Semite, born of the line of Heber and Shem.
Isaac was born of Abraham; then Jacob of Isaac. Jacob's name was changed to "Israel," and he fathered 12 sons. His sons and their descendants are called Israelites, and they would be both Semitic and Hebrew. However, this would not make either Abraham or Isaac "Israelites." Some, who interchange the words "Jew" and Israelite, call Abraham a Jew, even though Abraham was not even an Israelite, and the word "Jew" is not used in the Bible until 1,000 years after Abraham.
The confusing factor is that almost all Bible translations employ the word "Jew," which is a modern, shortened form of the word "Judahite." Every time you come to the word "Jew" in the Old Scriptures, you should read "Judahite;" and every time you come to the word "Jew" in the New Scriptures, you should read it as "Judean."
The descendants of Shem include Assyrians, Chaldeans, Aramaeans, Sabaeans, Arabs, and Hebrews. Modern Semitic languages include Modern Arabic, Modern Hebrew, Maltese and the Ethiopic Semitic creoles. Semitic religions include the Abrahamic religions, namely, Judaism, Christianity, and Islam.