Holier Than Thou - Biblical Contradictions

Was Keturah Abraham's wife or his concubine?

Genesis 25:1-2, "Abraham took another wife, whose name was Keturah. She bore him Zimran, Jokshan, Medan, Midian, Ishbak and Shuah."

1 Chronicles 1:32, "The sons born to Keturah, Abraham's concubine: Zimran, Jokshan, Medan, Midian, Ishbak and Shuah."

Both Genesis and 1 Chronicles agree on the names of the sons born to Abraham by Keturah, however, they differ as to her relationship to him.

"Sorrow is better than laughter: for by the sadness of the countenance the heart is made better. The heart of the wise is in the house of mourning; but the heart of fools is in the house of mirth." (Ecclesiastes 7:3-4, KJV)

"Then I commended mirth, because a man hath no better thing under the sun, than to eat, and to drink, and to be merry: for that shall abide with him of his labour the days of his life, which God giveth him under the sun." (Ecclesiastes 8:15, KJV)