Why this huge contradiction in the ranking of top 100 films between IMDb list and AFI list?

IMDB Top 250 is what the majority of citizens think (people like me and you), and AFI's Top 100 movies is what 1500 artists and leaders in the film industry think out of 400 movies.

All listings are variant depending on what criteria is used to judge them!

AFI whether deliberate or not, will always favour U.S. movies.

Just as B.F.I is likely to favour British movies.

Even if it's done on box office takings. Doesn't mean that every viewer enjoyed the film that was part of the rating.

Also worth bearing in mind is the fact that big studios get better marketing strategies.

If you are a small independent film maker, what chance do you have of getting your movie into a multiplex? Let alone get it advertised in press and tv/radio slots!

This is why you need to take all ratings(even with regard to academy awards) with a pinch of salt. Remember, only a few thousand people get to decide who wins oscars.and those are the movies that fill our cinemas.

Ever see a Kevin Smith movie? Imagine how hard he has to fight just to get his movies MADE. Let alone rated,advertised,shown.

For every ugh movie that gets made. Imagine the wonderful ones that never will be!