Isra' is the night journey of Prophet Nabi Muhammad SAW from Masjidil Haram to Masjidil Aqsa

Mi'raj where Prophet Nabi Muhammad SAW journey to Sidratul Muntaha to meet Allah 

The word Isra is referred to as "walking in night" and the root word of Miraj is Arooj which means; "going to a higher place". During this blessed night, Prophet Muhammad (Peace be upon him) journeyed to sky level to meet Allah (Glorious is He), and for this particular reason in Islamic history this journey is recognized to be as "The night of Isra and Miraj.

(FROM https://www.facebook.com/Prophet.MUHAMMAD.MayPeaceBeUponHIM/ )

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http://www.slideshare.net/Binti_Nazeer/isra-and-miraj-35343504