There are certain important distinction between the morphological and the syntactic structural levels: 1. Relative order in morphological structures is more rigid. 2. Morphological structures are more fused phonologically. 3. The internal distribution classes in morphological structures are smaller, especially in derivational formations. 4. Morphological distribution classes are less open to new members (i.e. they are less productive of new combinations). 5. Morphological structures are smaller. 6. Morphological structures do not readily admit internal pauses. 7. Morphological structures have a more limited substitutability of expanded expressions.
- Nida (1949), a pag.102

There is a definite parallelism between the subdivisions of structure and meaning. On the structural level we recognize allomorphs, morphemes, and grammatical sequences; on the semantic level we recognize allosemes, sememes, and episememes.
- Nida (1949), a pag.174