Their differences were first highlighted during the 2011 Arab Spring uprisings when the television channels respectively gave the Saudi and Qatari perspectives in their coverage of fast-developing events, analysts say.
The Arab Spring "led to a polarization in Arab media," says Saudi analyst Abdullah al-Shamry.
"Both channels became more concerned about delivering the opinions of their financiers than offering a professional and objective view," Shamry said, adding that both channels were "losing their credibility" in the face of other rivals.
Analysts appearing on Al-Jazeera and Al-Arabiya are selected carefully to back their positions, Shamry charged.
Ties were strained between Saudi Arabia and the new governments in Egypt and Tunisia dominated by the Muslim Brotherhood, whereas Qatar has strongly backed the Islamists on their rise to power.
The contrast was clearest in their coverage of the turmoil in Egypt since last month's street protests which were followed by the army's ouster of Muslim Brotherhood president Morsi.
"Al-Jazeera and Al-Arabiya covered the events in Egypt in two diametrically opposite ways," said Mohammed El Oifi, Arab media specialist at the Sorbonne university in Paris.
As Al-Arabiya aired live footage of the protests in Cairo's Tahrir Square against Morsi, Al-Jazeera split its screen to relay images of a pro-Morsi demonstration at another square in the capital.
And as Al-Arabiya hailed Egypt's "second revolution", most guests hosted by Al-Jazeera described Morsi's ouster as a "coup against legitimacy."
For Oifi, Al-Arabiya's position was "an obvious reflection" of the line adopted by Saudi Arabia, whose King Abdullah became the first foreign leader to congratulate Egypt's interim president Adly Mansour, hours after he was named to replace Morsi.
But Al-Jazeera "adopted a more hostile position towards the June 30 events than the state of Qatar which seems to have more or less accepted the fall of Morsi," he said.
When 53 mostly Morsi supporters were killed outside Republican Guard headquarters in Cairo on July 8, Al-Arabiya ignored the Brotherhood's version of the incident and highlighted the army's statements.
Early this month, several Al-Jazeera employees resigned over disagreements with the channel's editorial line.
NJF/NJF