In general, the terms "Nephites" and "Lamanites" are used with the same meaning for the first 500 years of Nephite history. The term Nephites refers to all those who followed after Nephi and to their descendants. The term Lamanites refers to those who followed after Laman and to their descendants. However, it is mentioned later in the Book of Mormon that there were no "ites" of any kind during the 200-year Golden Age immediately after the appearance of the resurrected Jesus Christ. (See 4 Nephi 17.)
After this 200-year period of righteousness, the terms "Lamanites" and "Nephites" are used again, but with somewhat different meanings than those used earlier in the Book of Mormon.
(For further information on the later use of these terms, see the material listed after 4 Nephi 20, 36-39.)