Sometimes the gemara asks מנא הני מילי and other times uses a different terminology for the same question - מנלן. Is there a difference?
In the sefer Marbeh Zikaron [p. 61 and see also Marbeh Amida p. 210] he claims that whenever the halacha follows a certain opinion the gemara says מנא לן while if this opinion is rejected by halacha the gemara will use the terminology מנא הני מילי.
This is a fascinating revelation and if anybody can prove or disprove it, I would love to hear from you.