Please could you tell me the difference between pads and blocks ?
Pads -These can be spiral bound or glued along one edge of the paper .This can be either the short edge (portrait) or the long edge (landscape).
Spiral Pads - are ideal for painting on location as you can keep all your sketches in the same pad and just flip over the page and start again.
Glued Pads - do not have the advantage of being able to turn the page but it allows a portable way of transporting the paper on location
Blocks -These are glued on all four sides with a strong backing board. Some blocks have an opening to allow the sheets to be separated when the panting is dry. The reason the paper is glued on all four sides is to help prevent the paper from crinkling when it is wet (cockling). The paper may still cockle in the large blocks but smaller ones are useful especially for location painting. They are convenient to take on holidays or trips.