The rest are five-character ancient poems (referred to as five-character ancient poems). The five-character poems before the Tang Dynasty are all ancient poems, such as those of Han Yuefu and Tao Yuanming.
The difference is mainly reflected in rice. Modern poetry has strict requirements for metrical poems, especially metrical poems (this is the origin of "metrical"), which are reflected in rhyme and balance. The definition of quatrains is not very clear, so there are quatrains (or according to this, quatrains are called "cut sentences", that is, four sentences are cut from metrical poems) and archaic quatrains, which can also be regarded as the category of archaic poems. .
The definition of archaic poetry is that anything that does not follow the rules of poetry or rhyme is archaic.
For example, Wang Wei's five laws and five ancient poems, Du Fu's seven laws (er, it seems to be off topic), and Li Bai's singing style (this should be defined as the category of ancient poems).
Well, this is the general difference. If there is anything unclear, you can refer to the narrative in Mr. Wang Li's Poetry Metrics, which is more authoritative.