4 sides, similarities.
http://wiki.answers.com/Q/How_is_rhombus_similar_t...

A rhombus is any equilateral parallelogram except a square. It's an
http://www.chacha.com/question/howisarhombussi...

All squares are rhombuses, but not all rhombuses are squares. squares have four congruent sides, the diagonals are perpendicular, but squares have four congruent angles.
http://answers.yahoo.com/question/index?qid=200812...

how is a rhombus different from a square: on a square, both of the diagonals equal
http://www.tutorvista.com/topic/howisarhombusd...
