Confused over this: is taking "no heroic measures" the same as "dnr"?

Yes: Do not resuscitate means not applying life support measures or performing cpr. Generally this means taking no "heroic" measures.

Can be...: "dnr" stands for do not resuscitate and this means, in the event of your heart stopping, no attempts would be made to resuscitate you. Resucitation is considered "heroic measures". But, under some circumstances, other treatments may be considered heroic as well, like mechanical ventilation, feeding tubes, etc. It is best to be specific as to what treatments you would want under what circumstances.