What is elision

[ashraf abdo]

It is known that elision means the omission of one or more sounds (such as a vowel, a consonant, or a whole syllable) in a word or phrase, producing a result that is easier for the speaker to pronounce. Sometimes, sounds may be elided for euphonic effect
Please I would be grateful if you could tell the difference between assimilation and elision

[مستر سعيد دراهم]

شكرا لك اخي الكريم

[الأستاذ نادي ربيع]

Assimilation is a common phonological process by which the phonetics of a speech segment becomes more like that of another segment in a word (or at a word boundary). A common example of assimilation would be "don't be silly" where the /n/ and /t/ in "don't" are assimilated to /m/ and /p/ by the following /b/, where said naturally in many accents and discourse styles ("dombe silly"). Assimilation can be synchronic being an active process in a language at a given point in time or diachronic being a historical sound change.
A related process is coarticulation where one segment influences another to produce an allophonic variation, such as vowels acquiring the feature nasal before nasal consonants when the velum opens prematurely or /b/ becoming labialised as in "boot". This article will describe both processes under the term, assimilation.
المصدر: http://en.wikipedia.org/wiki/Assimilation_(linguistics)