"think" vs "reckon"

[Vact]

Hi, there.

Can you explain the difference between "think" and "reckon" for me?
Are there any differences between the following two sentences?
1. I think it is and I reckon its an impossible question to answer.
2. I reckon it is and I think its an impossible question to answer.

Thank you!

p.s.:
I don't know the exact meaning of sentence 1. It comes from here: http://www.english-test.net/esl/learn/english/grammar/ei015/esl-test.php#six
Is the logic:
Someone asks me a question, but I think it's impossible to answer this question, because it's unmeaning. However, I still think that if there were an answer, it should be yes.

[Mordant]

"Reckon" is informal when it means "to guess" or "to have an opinion." In the U.S., that is almost exclusive to the South. When it comes to standard English, "realize" is the only answer that works.

I guess some possibility is so, but I have come to the conclusion (or realize) that it is not possible to know for sure.

[Vact]

OK, I see. Thank you!