There are numerous ways to compare rivers - by their differences, by their similarities and some of the criteria would be - length, discharge, size, sources, mouth, basin, tributaries, area through which they flow etc.
The links below will give you ample details to cover this.
Indus; Ganges
indus valley
The Ganges River flows through India, while the Indus River flows through Pakistan
Indus River system Ganges River system Brahmaputra River system
the Indus and Ganges River
The Indus and Ganges
yes
west
yes
The Ganges River is freshwater.
The Indus River is a famous river in India. Its length is 1,988 miles, and it flows through India, Pakistan, and China.
The Ganges River and the Indus River.