User blog comment:VirusKA/Should Challenges show the answers/@comment-25143095-20141001065926/@comment-25297120-20141001071252

1/ The major differences between them are how many step users have to take and how his/her code is evaluated.
 * Challenge: There are some finite steps (3 - 5) to complete the challenge. Then, the code is evaluated by an automatic parser/grader or whatever. This parser/grader is pre-programmed by KA staff.
 * Project: There is no limit. The code is evaluated by another KA user.

Let's take an example. Say, in Challenge, if you submit 2 + 3 = 5, the answer does not get accepted because the parser/grader just know 3 + 2 = 5. In Project, you can create a simple art or a masterpiece like Mona Lisa II but there is a chance that your project does not get approved, just because the evaluator does not like you.

2/ No, you don't need to complete projects to earn Computer Science Patches. You can earn some energy points if your project get approved though.

3/ Yes, maybe. However, as I said above, if your masterpiece does not get approved, it does not mean it is bad. Improve it a bit, and try again.