The difference is due to voting power of who ever voted.. so one whale can upvote 200usd whereas 100 minnows might only upvote 50cents.

You cant really predict it. All you can do is post with everything u have, and engage, engage, engage with people you resonate with. It will take time a lots of hard work to be noticed unless u are very lucky!

Steem on, just do it because you love it
The rest will come