Final answer:
The student's question confuses non-existent categories within U.S. legislative terms. There are no 'senators for life' or 'senitors by right' in America; all U.S. senators are elected to six-year terms and can serve an unlimited number of terms if reelected.
Step-by-step explanation:
The primary difference between senators for life and senators by right seems to refer to the distinction in how U.S. senators and other types of non-elected senators maintain their positions. However, the information provided and the student's question itself seems to be conflating two different terms or describing an incorrect category. In the U.S. context, all senators are elected to six-year terms and may serve unlimited terms if continuously reelected; there is no official category for 'senators by right' or 'senators for life.'
In the United States, the Constitution doesn't provide for senators to hold a lifelong position, and no senators are afforded the position by right outside of election or appointment to fill a vacancy. Traditionally, senators were elected by state legislatures, but since the 17th Amendment's ratification in 1913, senators have been directly elected by the citizens of their states. Because of this history, some might mistakenly refer to 'senators for life' as those holding office indefinitely through repeated reelection, but there's no formalization of this concept in U.S. law. Senators 'by right,' if the term were to be used in some other context, would imply they hold the position due to some legal right outside of election, which does not apply to the U.S. Senate either.
In summary, there is no formal distinction in the U.S. between 'senators for life' and 'senators by right,' as both terms do not apply to the American legislative framework. All U.S. senators serve six-year terms and are subject to reelection by their state's electorate. This understanding is crucial for comparing the structure of the U.S. Senate to other legislative bodies which might have different rules regarding the appointment or election of senators.