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What is the Research al tearsheet calculation really doing and why?

I don't seem to understand what alphalens tries to calculate and why

1) in Research I pick a factor. Use get_clean_factor_and_forward_returns(). Plot returns for Q5-Q1 cumsum(). The char is different from the tearsheet cumulative returns chart. Why? What is the tearsheet doing? Is it perhaps weighting returns by my score on top of doing Q5-Q1 ?

( it seems you have to click on View Notebook in order to see both charts)

2) what is demeaning? is this responsible for the difference? I saw the term in the alphalens code

3) I noticed that instead of returning my score (real value), I calculate their quantiles, and return quantiles as my score, then the tearsheet chart becomes Q5-Q1 cumsum(). So what should my score be? A real number that can be used to rank assets? Or quantiles? Or if the answer is "it depends" then in what scenario would I want to do one or the other?

If this is explained in detail in some lecture please let me know.

Thank you

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