New member here. Why do some people answer the question in the comment section? What is the difference between a comment and an answer?
You should take the tour
About 2/3 way down is an explanation
In short Answers are meant to answer the question. Comments are to ask for more info or clarity regarding the question.
Stack Exchange aims to build a database of community-specific questions and good answers. A 'good' answer should address and actually answer the question, provide good reasons for why it is a good answer (dictionary definitions complete with links and citations, or logical reasoning, etc), answer good questions, and be expressed clearly.
Comments to the question, on the other hand, are intended to be brief messages aimed primarily at improving the question: requests for the OP to post research they have conducted, requests for context or other clarification, etc.
I'd venture to say that the EL&U community is just about in full agreement on the above. The problem lies with answers that don't meet all the criteria for being 'good' answers.
In particular, otherwise-good answers to 'bad' questions are sometimes voted down. Answers that are correct but unsupported are sometimes voted down. Even if we discount the voting (they are 'meaningless internet points', after all), there is the issue of whether an unsupported answer achieves the aims of building the long-term Stack Exchange database. There is, of course, the question of how high individuals consider the bar is for the answer section - this varies from individual to individual.
Why do some people answer the question in the comment section?
These 'not-quite' answers don't fit anywhere but they especially don't fit in the answer section. Hence people post them in the comments section. There is a separate question about what to do with them.
In a more direct question about the moderators' views on comments in answers, one moderator deliberately posted a not-quite-answer as a comment. This appears to validate (to some extent) similar not-quite-answers in comments on the main site. Another moderator said that he is looking into this topic more comprehensively, and will perhaps provide something more definitive.