Echo : " The reflection of sound after 0.1 seconds after that original sound is know as echo " 
Reverberation : " The reflection of sound before than 0.1 seconds after the original sound is know as reverberation " 
the difference between reverberation and echo is that the echo is received by the listener after 0.1 seconds and the reverberation is received before 0.1 seconds. 
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hope so my answer is useful .....!
Tnx @fluffy
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