VIVO…OPPO…The oneplus….no matter which phone you purchase, they all come under the same parent company.
BBK ELECTRONICS-A backbone
Vivo and Oppo are wholly owned by BBK Electronics. And Oneplus is the subsidiary of Oppo. So no matter which phone you purchase, you will be the part of BBK Electronics.
VIVO- History begins in 2009
Vivo, a Chinese technology company that designs, develops, and manufactures all kind of smartphones, accessories, software, and online services. It was founded in 2009 in Dongguan, Guangdong.
Vivo will also sponsor FIFA becoming the official smartphone brand for the year 2018 and 2022 FIFA World Cup.
OPPO-History begins in 2001
OPPO is also a Chinese mobile manufacturer founded in 2001 at Dongguan, Guangdong.
Oppo will sponsor 2019 cricket World cup in England. Also, 2020 T20 World Cup which will held in Australia.
OnePlus- History begins in 2013
OnePlus is also a Chinese smartphone brand founded in December 2013. It is headquartered in Shenzhen, Guangdong. It also serves 42 different countries and many regions around the world as of March 2016.
It is the child company of Oppo.
Source: The Internet, WIKIPEDIA