Simple,
We have airmen, NCOs, Warrant officers, who cunningly hold a warrant and don't get saluted, and commissioned officers who equally cunningly hold a commission and do get saluted.
I think you are having problems with the rank insignia of the RAF rather than than the structure. The explanation is a little trickier, however I will attempt to explain.
Airmen's rank insignia consist of nothing, or propellors with 2 or 3 blades on, I shall allow you to guess which is more senior. A four bladed propellor indicated a Junior Techician, senior to a two or three bladed propellor but junior to a corporal, although this rank is being phased out.
NCOs have 2 or 3 chevrons. Three chevrons with the aforementioned four bladed propellor (only for technical ranks) and the three chevrons with a crown fro a Flight sergeant.
Warrant officers have the royal cipher.
Commissioned officers have a system of thin medium and thick stripes much like our Naval bretheren only admittedly more difficult to decipher form a distance. The more stripes and the thicker they are the more senior.
White band is a training rank.
As I alluded to at the beginning of this post the rank structure is rather simple although I will willingly admit that officers rank insignia may be hard to spot at a distance. Wasn't me that whinged about not being saluted though!