Smith scored 20 points of his points in the first half and Jennings helped out with 13 assists as the Pistons continued their recent dominance over the Cavaliers.
Andre Drummond provided 14 points with 11 rebounds and Greg Monroe contributed 11 and 11 for Detroit, which snapped a two-game home losing streak.
Cleveland got 21 points and seven assists from Kyrie Irving but fell for fourth time in five games.
Tristan Thompson supplied 17 points and six rebounds.
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