It's the exact same engine, 3.5L 2GR-FE V6.

 You can confirm this by checking the plastic engine cover of these cars. it will say 2GR-FE.

The hp ratings differ by 4, but that's just a gimmick with the Lexus using premium fuel. It can use regular fuel if you want to, but with 4 hp lower.

This is Toyota's universal V6 used in almost all of its V6-available cars including Lexus. RAV4 V6, Estima/Previa 3.5, Sienna, Camry V6, Highlander V6, Venza V6, Avalon, the list is endless. For Lexus, the RX350, RX450h and ES350 also use this engine.

The new Lotus Evora also uses this engine.