Daniel Inouye.
The difference is that the senior Senator has been in office longer than the junior Senator.
Maryland senior senator is Sen. Barbara Mikulski. Maryland junior senator is Sen. Bejamin Cardin.
Each state has 2 senators. The one who has been in office the longest is the senior senator.
He is the senior senator from Arizona.
There are 2 senators from each state each serving 6-year terms. The senator with the longer term in office is known as the "senior" senator while the other is known as the "junior" senator.
Carl Levin.
He is the senior senator from Arizona.
Dianne Feinstein
Hugh Segal
He is the senior senator from Arizona.
Yes she is the senior Senator and Susan Collins is the junior Senator.
Sen. Richard J. Durbin (D-IL). He is also the current Majority Whip.