When I explained this to my daughter I drew a straight line to represent policitcal leanings.
I put LEFT at one end, RIGHT and the other end, and CENTRE in the middle.
I tried to simply explain the difference between left and right in political terms.
In then put Labour just left of CENTRE, Conservatives just right of CENTRE with libs dems over CENTRE.
I then put Communist to the very left, and Facist to the very right. Socialist I put on the LEFT, but not as far left as Communist.
This is fine for a 13 year old, but of course is does not explain why Stalin, who was head of a communist state, was probably more Fascist than Hitler.
Maybe my straight line actually joins up at either end to form a circle.