Is Lombok Part of Bali?

No. Lombok and Bali are two distinct islands in Indonesia's Lesser Sunda Islands chain.

• Lombok Strait (20–40 km wide) separates them—part of the Wallace Line, a major biogeographical boundary
• Bali is west of the strait; Lombok is east
• Different cultures: Bali is predominantly Hindu; Lombok is predominantly Muslim (Sasak people)
• Different landscapes: Bali = volcanic, rice terraces, tourism hub; Lombok = drier, Mount Rinjani (3,726 m), quieter beaches

They are neighboring islands, not the same island.