Dependent and dependant are two different words entirely; as such, the two words are not most times confused in terms of meaning. Dependent is an adjective that means relying upon or depending upon. For example, the financial hardship I went through made me become more dependent on my friends.
Most times, when this word is used, it means someone depends on another person for certain provisions. Also, we are living in a world where some people seriously depend on substances for survival. These people are usually referred to as substance-dependent individuals.
On the other hand, the word dependant is a noun, unlike the word dependent, which is used mostly as an adjective. It is used mostly for people who depend on other people for support, most especially financial support. However, in some countries, the word dependent is also used as a noun and has the same meaning as the word dependant.