If you review a document, it means you read it and examine it (and maybe have some ideas to improve it) - but you don't make any changes.

If you revise a document, it means you change the text to correct errors or make improvements.

When preparing for a test, it's a good idea to study the material again in order to refresh your memory. American English speakers say you are reviewing for the test. British English speakers say you are revising for the test.

Fact
The smallest bird in the world is the 2.3-inch hummingbird. It counteracts the forces of gravity by flapping its wings over 200 times per second.      .. More >>