Final answer:
A button magnet attracts an iron pipe because the magnet induces a temporary opposite magnetic pole in the closest part of the iron, causing attraction. They don't repel each other because iron doesn't have a permanent magnetic field and thus doesn't have fixed poles to repel the magnet's poles.
Step-by-step explanation:
When you bring a button magnet close to an iron pipe, the iron pipe is attracted to the magnet because ferromagnetic materials like iron have the property of enhancing the magnetic field they are subjected to. In contrast to magnets, which have two poles (north and south), the iron pipe does not have a permanent magnetic field. However, under the magnetic field of the button magnet, it becomes temporarily magnetized with opposite magnetic poles nearest to the magnet, which is why they attract rather than repel each other.
Like magnetic poles will repel each other, such as if the north pole of one magnet is brought close to the north pole of another, the magnetic field lines will bend away indicating a repulsive force. Conversely, opposite poles attract, and when a magnet interacts with unmagnetized iron, the attraction is due to local magnetization with unlike poles closest to each other. This can be demonstrated by magnetizing a metal knitting needle with a bar magnet and then observing that the needle can in fact attract paper clips or show repulsion if the like poles of two magnets are brought together.