American pool is a term used in the United Kingdom, and sometimes more broadly outside North America, to refer to pool (pocket billiards) cue sports that make use of formerly American-style and now world-standardised numbered billiard balls that have a standard diameter of 57 mm ( 2 1⁄4 in), as opposed to British-style unnumbered 56 mm ( 2 3⁄16 in) balls. Other "American" pool differences from British-style pool include larger pockets to accommodate the bigger balls, and diamond system markings on the rails.
The term may apply to any pool game variety using such a ball set, and is commonly applied especially to the most internationally competitive of these sports:
References
American pool Wikipedia(Text) CC BY-SA