Full Idea
Properties are often taken to be intensional; equiangular and equilateral are thought to be different properties of triangles, even though any triangle is equilateral if and only if it is equiangular.
Gist of Idea
Properties are often seen as intensional; equiangular and equilateral are different, despite identity of objects
Source
Stewart Shapiro (Foundations without Foundationalism [1991], 1.3)
Book Reference
Shapiro,Stewart: 'Foundations without Foundationalism' [OUP 1991], p.16
A Reaction
Many logicians seem to want to treat properties as sets of objects (red being just the set of red things), but this looks like a desperate desire to say everything in first-order logic, where only objects are available to quantify over.