First, the sentence pattern of children's songs is relatively standardized, but children's songs are not.
Second, nursery rhymes pay attention to feet, but children's poems don't.
Third, how short nursery rhymes are, and children's poems are not restricted.
Fourth, nursery rhymes are simple and easy, and children's poetry is artistic.
Fifth, nursery rhymes are easy to compose and sing, but nursery rhymes are not.
Nursery rhymes are not only amusement tools for talking, learning, teasing and singing, but also shoulder the heavy responsibility of children's education.
Also, here is an article that distinguishes nursery rhymes from nursery rhymes. The landlord can look at wclrc/drafts/Taiwan/Wu/Wu-01.htm.