A business account on WhatsApp can either be listed as an "Official business account" or a regular "Business account".
NOTE: Currently "WhatsApp Official Business accounts" are in a VERY early phase and rarely approved by WhatsApp. We can request an Official Business Account for you, but we cannot promise when or if at all you will be granted a WhatsApp Official Business account.
Listing a business as an "Official business account" is based on a variety of factors, such as whether the brand is notable, but most of all on the opinion of WhatsApp. A business can't request or pay to turn a "Business account" into an "Official business account" and is not 'entitled' to an Official business account.
An official business account can be recognized by the green check behind your company name.
A middle tier of "verified" accounts used to exist, but this tier was deprecated by WhatsApp in early 2019.