No, both shapes have all four sides equal.
Square and rhombus.
It isn't really a square if it has no equal sides. A trapezoid can be drawn that has no equal sides, some can have two sides equal. Quadrilaterals include those 4-sided shapes with no sides equal but they also include all other 4-sided shapes. You would need to specify "Quadrilateral with no equal sides".
A square is a regular polygon with 4 equal sides and 4 equal interior angles.
It is a square as square has 4 sides and all of them are equal. Also it has 4 corners.
No, octagons just have to be closed shapes with eight sides - the sides do not have to be of equal length.
There are a few simple shapes with equal sides. The basic shapes are a square, octagon, and an equilateral triangle,
Most shapes do not have equal sides. In nature, shapes with equal sides are the exception rather than the rule.