Many people use the phrases “sight-word” and “vocabulary word” interchangeably, when they are quite different. This confusion, I believe, serves a sinister purpose for our Education Establishment.
A sight-word is a one-dimensional object. You know it visually, that’s all. When you see the graphic design, you are supposed to respond in an automatic or conditioned way. You say the sound represented by the design. The Education Establishment pretends this is “reading” but it’s not.
On the other hand, a vocabulary word is a multi-dimensional object. Most importantly, you know it phonetically. You say the sounds represented by the letters. This is real reading although the Education Establishment would like to pretend otherwise.