For KrisFlyer members, does it make any difference if you call Ticketing and Reservations hotline or Krisflyer membership hotline to ask about your reservation?

Normal ticketing won't be able to handle KF related matters (or not in their scope)

You will be re-directed to the KF hotline. The ticketing do not handle redemption

They will direct you to the "Krisflyer Membership hotline" if you intend to reserve a seat with your aiirmiles. Airmiles redemption have to be made via "Krisflyer Membership Hotline"

This really depend your luck, we cant predict which hotline has lower call rate daily, i will suggest to choose english agent is easier to get thru than other language. and call at midnight better, singapore airlines' customer mainly in asia, midnight mostly are sleep.