1. Do we need to know both glob and regular expressions for the exam?
2. What is the basic difference between these? Or rather why do we need globs when we have regex?
3. Why do globs only work with files?
1) For the Java 7 exam, yes. You need to know the basic syntax of both. (For the Java 6 exam, you only need to know regular expressions, but not globs.)
2/3) Globs are used for files. They are different then regular expressions. For example, it makes sense to say "match all files/directories regardless of level" which is a glob concept.