Height is not the only thing to take into consideration, yes 14.2 is the traditional cut off, but many breeds societys of small horses don't like to refer to the breed as a pony.
Shetlands are known throughout the world as ponies, in Shetland an old crofter will ask you if you keep horses, in which case he means Shetlands, if me means anything else he will say "big horses"
I think it is more accurate to refer to a pony as something bred specifically for kids to ride, a small horse breed is one bred for centuries to carry adults and work in industry or ariculture.
Icelandics never get much bigger than 14hands, but they are horses, there is no word for pony in Norse languages.