[Orgmode] refiling

[Richard Riley]

I'm a bit rusty so please excuse any stupid questions.

I decided to clear up my org files which are, frankly, a mess.

Two major issues for me to get my head around.

1) Tags v Categories. Its not entirely obvious to me what categories are
for. Are they like a more specialised tag?

2) Refiling. Lets says I have something like this in linux.org:-

* general    :general:
#+CATEGORY: general
** learn org mode   :emacs:org:
blah blah
* debian    :debian:
#+CATEGORY: debian

* test

if I refile from elsewhere, it picks ALL items at a level to refile to when I 
select
linux.org. 

e.g linux.org/general, linux.org/debian, linux.org/test

If I then select "general" it also prompts for me now to select "learn
org mode". Is this because of some hangover from me using org-mode? In
other words I cant refile to linux.org/debian.

Wise words appreciated to put me back on track.