Is there a moral difference between killing, and letting die?

In short, yes there is a moral difference between killing and letting die, but not always. But the issue with these kind of moral dilemmas is that there is no single answer, and everything lies in the circumstances of the situation and decisions that are made. I will cite for an example the recent cruise ship wreck off the coast of Italy. The Costa Concordia capsized killing 17 people and the captain is charged with abandoning the ship before all of his passengers were safely evacuated. Some people in Italy want to charge this man with murder! But when you look at the circumstances, you might agree that all this man is guilty of is cowardice and recklessness. Unlike murder, the decisions he made were not based in malicious intent, but rather in self-preservation and fear which is only human, which is just about all we can ask a person to be. But if the situation were different, and the actions that would prevent someone's death were reasonable, letting die brings with it certain guilt. I will cite another situation in New York where a homeless man, Hugo Alfredo Tale-Yax was stabbed multiple times and left in the street to die after saving a woman from the attacker in Queens, New York. A total of twenty-five people walked passed the collapsed and dying man without coming to his aid. After an hour and a half someone finally shook Hugo and he was rushed to the hospital where he was pronounced dead at age 31. In this situation, any one of those passer-by's could've easily called for help on their cell phone or gotten the attention of someone who could. In my opinion, when letting die comes down to a decision such as this and you let someone die, you are almost as bad as the murderer. And another possible scenario for consideration, letting someone die intentionally where you had the direct chance to intervene, but chose not to so that the person would die. For example, you're on a hike in the Amazon and you come across your long time enemy waist deep in quicksand. You have the necessary gear to help them out, but instead you ignore their cries for help and keep walking. In my opinion this murder all the same because the intent to kill was there.

Greetings comrades

     My name is Chris McCann, 18 years old ( 19 this Sunday )
I come from Dalton, MA... about 30 minutes from MCLA. Studied at Wahconah high school in the same town, ended up being class president for senior year. Anyways... I'm interested in philosophy because I love thinking. ( We're talking about someone who contemplated the meaning of life and death since the 4th grade. ) I love the word "Why?"
Thusfar I have taken classes in psychology,  humanities (the study of Geniuses), and sociology. I found these classes to be the most rewarding because I of the thought involved, this is why I decided to take this course.
     In my spare time I enjoy making music with my guitar, computer, and any other instruments I might have handy. I've dabbled in painting, photography, writing, and drawing but guitar and music is my strong suit. Currently I'm on a nu-jazz kick that combines the influences of Jazz music with rock instrumentation and electronica-esque use of synthesizers. This of course with my usual love of classic rock, modern indie, old pop music ( think Beatles era pop ), and post-alternative or progressive "metal" (generally nothing heavier than Tool), and chilled out artists like Bonobo are my favorite.