Hello Friends,
What does the first thing click in your mind when someone ask you what's your aim / passion in life ? Ya, I believe that situation wise, both the words means in versatile pattern. But both these words makes confusion when we deeply think why there's a point blank or big difference in between both the things in most of our life ?
I hope you are getting me 
... In my word, passion is that which comes out of our will of internal heart & for which we forget everything to achieve , but AIM pertains to various criteria like in childhood we always think to be that which our passion-ism asks to be, but again from college time it drastically changes to that through which we can utilize our whole life study to earn for our living & also to feed our passion (most of the times, out of busyness we even forget what passion means in our life) . Very few lucky people or we can say smart working people who lives their life according to the rules of their passion and earn without even altering the process of passion-ism in their life........ A grand salute to those who dares to live their life with all protocols of passion-ism .
Well !! I guess most of us can't say that our passion itself is our aim because of various regularities of our life story. For this we can take the scenario of dream aka passion of a poor child whose aim deviates from passion in time due to fulfilling family need. In this real word we can correlate all the heap of burdens or calamities of our life which stands as a barrier in between our passion and forcibly molded definition of aim .
....... don't know what else to say, but I would love to hear from you guys about feelings on this 
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Regards,
Nilutpal.