Twist pile
This popular style gives a rougher surface area achieved by twisting the yarn an extra turn or two.  The carpet is then less prone to showing footmarks. Yarns can be wool or man made and are described as either "Hardtwist", "Frise" or "Hightwist". 

Velvet
This carpet has a a short pile and smooth top and is sometimes known as Velour. Available in wool or synthetic fibres and mainly in tufted and Wilton finishes.

Saxony
This style is available in several different fibres. The tufts tend to be closer together and the pile shorter than in shag pile carpets.

Loop Pile
Available in both wool and man made fibres. Carpets come in natural and "Berber" colourways.

Shag Pile
A luxury carpet available in heavy weights.  Excellent for decorative purposes and to make a real statement in a room.