So what is the difference between morality and ethics? I've come up with my own understanding of the difference but would be interested in what others might think.
The difference between the two as I see it is that morality is a gut feeling. It's your inner sense of right and wrong that has developed over the course of your life. Ethics is a set of specific rules, often written down, that state right behavior and wrong behavior.
So to use the Bible as an example, the sense that it is wrong to kill within the tribe (but not outside the tribe) is morality. The Ten Commandments would be a set of ethics.
I think that makes sense to me. Ethics can be consider a formal study of our morality. Listing those moral rules would be part of it.
Although as I write this it occurs to me that ethics is more than just a study of what is, it is also a study of what should be. Many groups, business and advocacy groups, will try to create ethical rules which they think people should adhere to.
Some useful resources:
quotation: "[Ethics is] is the philosophical study of morality. The word is also commonly used interchangeably with 'morality' to mean the subject matter of this study; and sometimes it is used more narrowly to mean the moral principles of a particular tradition, group, or individual. Christian ethics and Albert Schweitzer's ethics are examples."
-- John Deigh in Robert Audi (ed), The Cambridge Dictionary of Philosophy, 1995
Word of the Day - Morality vs. Ethics
Broadly speaking, morals are individual principles of right and wrong, and a system of ethics deals with sets of those principles. Both terms entered the language in the Middle English period, with moral being the older form by about 100 years (c. 1300).
Article on Atheism.about.com: What are Ethics and Morality?
The way I think about the distinction is similar to what you mentioned: ethics are on the outside/external and morals are in the inside/internal. Ethics can be situational and we take context into account...historical context, cultural context, etc. They are rules...guidelines.
I think of morals in absolute terms and ethics in relative terms. It may be considered immoral to kill, for example, but ethically acceptable to end suffering. When moral values and judgments are applied in a real setting, that equals ethics. Ethics boards in hospitals, for example, will reach consensus with families about 'end of life' decisions. The whole discussion about 'death panels' brought up by the Republicans during President Obama's health care reform plans paint a broad brush about palliative care and hospice care that oversimplifies the real moral dilemmas families face every day....human values, attitudes, judgments are subjective!
In the field of psychology, we're taught that morals are our own values. Ethics are the code set for us that determine right or wrong in legalese. Our instructor gave us an example: What would you do if your client came in and told you they murdered someone last night?
The moral answer would be to report it because somebody died and this person could get away with it. The ethical answer would be that you cannot break confidentiality, as a psychologist, as this client is not currently threatening to kill someone.