The definition of poetry is too big. Therefore, "Spring and Snow in Qinyuan" is a poem, but the accurate classification should be a word. Ci is just one of the expressions of poetry. Qinyuanchun is a epigraph name. The so-called Tang poetry and Song poetry are still very different in expression techniques.
The development process of poetry: The Book of Songs → Songs of Chu → Yuefu Poetry → Folk Songs of Wei, Jin, Southern and Northern Dynasties → Tang Poetry → Song Poetry → Yuanqu Poetry → Ming and Qing Poetry → Modern Poetry.