There are 3 different products within the WhatsApp ecosystem:
1.
WhatsApp Messenger - for private individuals. Probably, you are already using it.
2.
WhatsApp Business App - for small businesses who personally manage conversations with customers.
3.
WhatsApp Business Platform (a.k.a. WhatsApp Business API) - for businesses communicating with customers at scale, automating most part of their communication, and for collaborative teams.