Cause and effect are two different concepts. Using one or the other depends on what part of a situation you want to stress. Stating the causes and/or effects of a topic is helpful in persuading readers to make a decision about a topic.
Causes tell readers why something happened. For example, numerous stolen bikes on campus cause students to register their bikes. Smoking causes lung cancer. Typing for many hours causes carpal tunnel.
Effects are the results of something. For example, fifty new bike racks were put on campus with funding from registered bikes. Twelve hundred smokers die every year from lung cancer. Carpal tunnel is now discussed in many employee training programs.