There are different types of graduate assistantships. The broader term of Graduate Assistant refers to all three types of graduate assistantships. The categories are as follows:  

• General Assistant - renders general service to an academic or administrative unit.
• Research Assistant - performs scholarly activities, such as conducting experiments; organizing or analyzing data; presenting findings; collaborating with others in preparing publications or productions; and conducting institutional research for an academic or administrative unit.
• Teaching Assistant - performs instructional duties, such as providing or coordinating classroom instruction, including lab or discussion sessions; tutoring students; grading tests and assignments; developing instructional materials; providing artistic instruction; accompanying/coaching musical or vocal performances; and proctoring exams.