This question, Which DOM elements cannot accept an id?, shows research effort. The op cites material from the spec and also explains what he's learned so far about the id attribute. He's asking for an answer that still could probably be found by google searching, but it's not so bad that I could find it in 10 seconds on Google without thinking about it. IMHO, this question is a good example of how to ask a question where the answer might not really be that complicated.
In the second question, PHP - Differences between those functions, the op simply asks "What is the difference between X and Y". The op gives us no indication of what research this person has already done on the two functions or what specifically the op doesn't understand about the two. Also, the PHP site has so many examples of usage that it's redundant to ask for examples of usage on StackOverflow. Instead, the question could have actually been a little better if the op first showed the two examples, found through his own research, explained what they both were doing, and then asked the community to explain what the difference is.
In short, the main difference between the two questions is simply in the amount of effort put into composing them. We don't dislike easy questions or questions that are somewhat "amateur", we just want those questions to be asked by people who respect the community's time and give us enough information to more definitively answer the question.