With the aid of examples, distinguish between inflectional morphemes and derivational morphemes.

Modern English is a language that uses inflections to denote grammatical properties such as possession, comparison, number and tense. Inflectional morphemes, therefore, are the suffixes we add to words in order to denote these properties: so, for example,
-'s is an inflectional morpheme which indicates possession ("Sarah's book")
-er is an inflectional morpheme indicating comparison ("bigger than that")
-s is an inflectional morpheme which can indicate that something is plural ("cat" becomes "cats"); the archaic inflectional morpheme 'en' can also indicate plurals ("ox" becomes "oxen")
-ed is an inflectional morpheme indicating tense: "he visits" becomes "he visited"
A derivational morpheme, by comparison, creates a new word deriving from the same root as the original word, but turns it into a different part of speech. This process is also called transformation. For example, adding "ly" to the adjective "quick" turns it into an adverb. Adding "ful" to "delight" turns it from a noun into an adjective.

Inflectional morphemes are words that are created from a lexeme, or a basic unit of meaning in a language, without creating a new category in one's lexicon. An example of an inflectional morpheme is "books," which is created from the word "book." The new word that is created is in the same grammatical category as the original word (in the case of "book" and "books," both are nouns). Other inflectional affixes (affixes are added to the root of a word) change the word with regard to tense, case, and gender, such as "brings" from "bring" (changing tenses); "Mary's" from "Mary," (changing cases); or "masseur" from "masseuse" (changing gender). 
On the other hand, derivational morphemes are words that have different lexemes from the original word. A derivational affix can produce a word that's in a different grammatical category from the original word. For example, adding "ly" to the word "quick" changes the grammatical category of the word "quick" (as "quick" is an adjective, and "quickly" is an adverb). In addition, a derivational morpheme can have a very different meaning than the original word. For example, if you add "non" to "sense," you produce the word "nonsense," which is in the same grammatical category as the first word (both are nouns). However, "nonsense" has a very different meaning than the word "sense." If an affix changes the part of speech of the word or the meaning of the word, it is a derivational affix.