Share-based transaction and Business Combination transaction

Hello Sir,

What is the difference between a share-based transaction and a business combination transaction.

For example if Entity A purchases all share capital of Entity B which is owned by directors and the directors are paid in terms of entity A’s shares.

Is the share payment not the purchase consideration and since it Entity A has purchased all the share capital of B, does Entity A not have control of B? Should it not be a treated as a transaction in business combination rather than a share-based payment transaction.

Please clarify on this matter.
Thanking you in advance.

Regards,
M