"Because morphemes provide meaning cues as well as decoding and spelling patterns, learning how to use the morphemes in large words helps you to build your meaning vocabulary. Wide reading is the most significant predictor of vocabulary size and the best guess of experts is that you use context and morphological clues together to infer meanings for new words you encounter in your reading." (Cunningham, P. M., & Cunningham, J. W., 2002, "Children Decode," para. 3)
Morphology is using the smallest units (morphemes) to build meaning or maintain grammar. A few examples of the types of morphemes we add to various parts of speech would be "s" at the end of nouns to make a plural, "ed" at the end of verbs to form a past tense of the word, or "est" on the end of an adjective to form a superlative. Knowing that adding an "s" at the end of the word "book" adds the meaning of more than one book, would be morphology. Making meaning of the word "photograph" from the Greek roots of "photo" and "graphos" would not be labeled as morphology, but rather etymology.