The first attack near a cultural center in the town of Azaz killed six civilians including a young girl, the Britain-based Syrian Observatory for Human Rights said.
An AFP reporter at the scene saw a mangled car ablaze, black smoke billowing into the sky.
A man rushed away from the site of the blast, carrying what appeared to be a child wrapped in a bloodied cloth.
In the second incident, a car bomb targeted a checkpoint of pro-Ankara rebels near the town of al-Bab, killing five fighters, the Observatory added.
Areas of Syrian Kurdistan held by Turkish forces and their Syrian proxies are regularly rocked by such bombings.
There is usually no claim for them, although Turkey routinely blames Kurdish fighters it accuses of being "terrorists" linked to its outlawed Kurdistan Workers' Party (PKK).
On Saturday, explosives planted in another vehicle took the lives of eight civilians including four children in the city of Afrin, which Turkish forces and their proxies seized from Kurdish forces in 2018.
Syria's war has killed more than 387,000 people and displaced millions since starting in 2011 with the brutal repression of anti-government protests.
It has since evolved into a complex conflict involving jihadists and foreign powers.
Northern neighbor Turkey has seized control of several regions inside Syria in military campaigns against the Islamic State group and Kurdish fighters since 2016.
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