The following map shows the opposing camps in Syria and Iraq. The Alawite part of Syria is supported by Russia and Iran, the Sunni part of Syria is supported by the Turks and the Arabs of the Persian Gulf, and the Kurdish part of Syria is supported by the Russians and the Americans.
When I say that the Russians and the Americans are supporting the Kurds of Syria, I do not mean that there is a friendly cooperation between the US and Russia. On the contrary, the Americans and the Russians are competing for influence over the Kurds of Syria. The same is true for the Alawite part of Syria, where the Russians and the Iranians are competing for influence over the Alawites, and also for the Sunni part, where the Turks and Arabs of the Persian Gulf are competing for influence over the Sunnis of Syria.
In Iraq the Sunni part is again supported by the Turks and the Arabs of the Gulf, the Shia (Shiite) part is supported by the Americans and the Iranians, and the Kurdish part is supported by the Americans. Again the powers supporting the same side are competing for influence.
There is the exception of the Iraqi Kurds. For the Iraq Kurds the US is the perfect ally. That is not true for the Kurds of Syria (YPG), who are cooperating with the Kurds of Turkey (PKK), because the Americans have designated the Kurds of Turkey (PKK) as a terrorist organization. Therefore the Russians have an advantage over the Kurds of Syria, because after the Turkish-Russian relations went sour, the Russians do not have to worry whether the Kurds of Syria will pass the Russian arms to the Kurds of Turkey. On the contrary, the Americans have to ensure that the arms they give to the Kurds of Syria will only be used against the Sunni Islamists of Syria (ISIS), and not against Turkey by the PKK.
The Kurds of Iraq are rich in oil and gas and they need Turkey to export their oil and gas, while the Kurds of Syria and Turkey want a share of this oil and gas, and until they get it they will not need Turkey, and they keep working with Russia. That creates tensions between the Kurds of Iraq (KRG) on one hand, and the Kurds of Syria (YPG) and the Kurds of Turkey (PKK) on the other.