What word means someone who is above another?

Superior or less commonly 'supraordinate'.

Conversely a person below another is Inferior or subordinate.

However, ther use of these Words depends on the contect thay are being used.

Quite often 'Senior' is used instead of 'Superior' , but 'senior' means older.

Conversely ' Junior' is used instead of 'Inferior' , but 'junior' mens younger.