I just love the rainbow display of perceived competence/understanding in the debatement of these 2 words lol..you'll find arguments that range from comically ignorant, to simple but precise, all the way up to over elaborately intelligent. Its great! (Is over elaborately even a "word"/grammatically correct in this case? I initially typed, "...overly elaborately intelligent[.]", but ultimately chose to edit it. Looks like I found the next subject of/to^ debate! ^ Which is correct; '..subject of debate[!]' or '..subject to debate[!]'? Look at that, I found yet another!)
Although I am being genuine in what I've just written, I also did so to illustrate just how endless the list is when it comes to the amount of things that can be debated over when it comes to language-ESPECIALLY the English language. While some of them do actually have a clear/concise right or wrong answer, many are subjective to culture, location, topic, situation, &/or opinion. This topic def belongs to the latter. You would have to assess the context of the situation in order to choose which form of the word is more fitting. However, as a [very] general rule, I typically see/use/refer to 'obligated' as more of a negative sense of the word &'obliged' as the more positive sense. I can actually remember the specific situation that developed my understandings in this manner..it goes all the way back to me being 8 years old watching the timeless,classic Tim Allen movie, Jungle 2 Jungle (which is still as entertaining to watch now as it was then) when his young teen/pre-teen son(who has come to live with him in urban America after being raised in some village tribe that most would refer to as 'uncivilized') asks him what 'obligated' means, when Tim Allens character is explaining to him that he has to leave for the day to go to work. He explains it as, "..something that I have to do that I don't necessarily want to do." Tims character has a gf who is very unaccepeting of his son&his odd ways of behaving& during a phone conversation with her, Tims character uses the word 'obligated' when it came to what his reasons were for going to get his son/allowing him to stay there,which his son over hears and obviously gets upset. Because he now thinks his dad never wanted him to come home with him, he only did it because he had no choice. If you haven't seen the movie, you need to stop what you're doing right now,& go watch it. You can thank me later. Anyways, that's my take on this matter.. Hopefully it's of some use to someone.