Dying willingly vs. suicide

No, they are not necessarily the same thing.  I do not know the context of your question, but I can think of situations in which people would give up their lives for others (“dying willingly”), and their deaths would not by any means be considered suicides.  I think of a soldier in combat, throwing himself on an explosive device to shield his fellow soldiers.  That is an act of amazing bravery and sacrificial love, not a suicidal action.

The distinction between “dying willingly” and “suicide” is one that Jesus also made.  He said, “Greater love has no one than this, that he lay down his life for his friends” (John 15:13).  And of course Jesus did more than talk about laying down his life.  He did that.  He laid down his life for people who were his enemies, not his friends, because of sin and unbelief.  What a Savior we have in Jesus!