Translation:The square and the rectangle are different shapes.
A square has four sides of the same length, and four 90 degree angles between them. A rectangle has the angles, but the sides don't necessarily need to be all of the same length. Thus, all squares are rectangles, but not all rectangles are squares, much like thumbs and fingers. In case anyone was wondering :P
A quadrangle is not usually a shape in English. It is a courtyard surrounded by buildings. It does not actually have to be four-sided, but usually is. The correct word is quadrilateral. A rectangle is a quadrilateral (a four-sided polygon) but a quadrilateral can also be some other four-sided shape such as a square or parallelogram. Thus, the quadrilateral and the rectangle are the same shapes in some circumstances.
Ah, δεν είναι σωστό, όλα τα τετράγωνα είναι ορθογώνια! Μα όλα τα ορθογώνια δεν είναι τετράγωνα =)
Does τετράγωνο mean "square" or does it mean "quadrangle", as a literal translation would suggest? The two are not the same.