Frizzle is a term used to designate that a chicken posesses the gene that cuases their feathers to curl. Frazzle, more commonly called curley is when the bird has two copies of the frizzle gene, which over curls the feathers and causes structural problems with them--they become brittle and break, often leaving a nearly naked chicken.
Frizzle can occur, and is recognised for every breed: frizzled blue cochin, frizzled barred rock, frizzled mille fleur d'uccle, frizzled bbr oegb, frizzled red pyle asil, etc.
Sizzle is essentially a frizzled silkie without silkie feathering; a frizzled silkie would have silkie feathering. Sizzle is being worked on as a new breed, not as a new variety of silkie.