宫殿 (gōng diàn) is the general, neutral term for a palace — a large, splendid building where a monarch resides. It's more common than 皇宫 (huáng gōng 'imperial palace'), which specifies a palace of an emperor, and differs from 宫 (gōng), which is broader (can mean a public hall like 少年宫). 宫廷 (gōng tíng) refers to the imperial court as an institution, not the building itself.