Answer:
Irish people wear no different clothing to anyone else. However Arann knitwear, which comes from a small island of the same name (Arann) creates knitwear that is distinctly Irish, and are very popular with tourists.
Additional Information:
http://www.shamrockgift.com/product/irish-hand-knitted-womens-cardigan
http://www.the-irish-path.com/irish-traditional-clothing.html