The SAT and ACT are both admissions tests used for admission to U.S. colleges. The SAT tends to be used more in the Eastern and Western parts of the U.S. The ACT tends to be used more in the central part of the U.S.
The college you are applying to will make it clear which of the SAT or ACT is required.
The tests are similar in content and objectives. The ACT includes a Science component.
The ACT contains multiple-choice questions in each of: English, Math, Reading and Science.
Information about the ACT may be found at:
http://www.actstudent.org/regist/dates.html
Free ACT prepatation material may be found at:
http://www.actstudent.org/testprep/index.html
A free 80 page ACT prep guide may be found at:
http://www.act.org/aap/pdf/preparing.pdf
Online ACT Prep is available at:
http://www.actstudent.org/onlineprep/index.html
It is quite inexpensive.
Please note that Canada is NOT treated as a “foreign country” for the purposes of ACT registration.