Economy vs Standard
The difference between Economy Mats vs Standard Mats is simply the 'core color'. The core color is the visible part seen on the beveled edge of the cutout (see images below). Economy mats have a cream core or 'natural' white hue. Standard mats have a white core, where the 'natural' color has been whitened using optical brighteners.
Other than that, our Economy and Standard mat boards are the same. Same thickness. Same acid-free qualities. Many people like the bright white beveled edge of the Standard Mats for a cleaner, more professional look, while others like the savings of the Economy Mats with the cream core beveled edge.
1) Shown here: an Economy Mat, which are 'Cream Core' (the beveled edge is cream colored)
2) Shown here: a Standard Mat, which are 'White Core' (the beveled edge is a bright white color)
3) Shown here: a Standard Mat with the 'Black Core' option (the beveled edge is black in color)