The primary difference between a between a WhatsApp Verified Business and a WhatsApp Official Verified Business is that the inbound message is identified as being from the business name with an official account and from the number with a regular business account.
A business account on WhatsApp can either be listed as an Official business account or a regular Business account. A business can't request or pay to turn a business account into an official business account. At this time, only certain business accounts are listed as official business accounts. Listing a business as an official business account is based on a variety of factors, such as whether the brand is notable.
Following a series of client rejections, Sinch has requested further official guidance from WhatsApp regarding business verification. WhatsApp have committed to refine and publish their approval criteria in July and we will provide a link to this here as soon as we receive it.