Height and width
usually refer to the printed area of the stamp, but not always. The catalogue should make it clear when it's talking about perforation to perforation height and width. As an example of what I mean, take these two (different) stamps from Barwani State in India:

The stamp on the left is classed in Gibbons as a 'Close setting' (SG 35A); the stamp on the right is classed as a 'Wide setting' (SG 35aB). The stamp on the left is priced at £6; a pair of the stamps on the right just sold at auction in the UK for £1050.