Compare two data sheets for common entries

Hello All,

I have two data sheets containing approximately 11000 and 8700 entries respectively. I need to compare the data sheets such i find out the common entries and unique entries. Sheet 1 has a unique column containing age data and sheet 2 has that of NARI No( an ID number of my project). I tried using vlookup but failed doing so. i am a biologist with little knowledge of excel. please help.

thank you!