Digitization is associated with cost-cutting and operational excellence. It is incorporating digital technology into the company’s core operations, like accounting and invoicing. It involves standardizing business processes.
Becoming digital is focusing on the customer-centric value proposition. It integrates digital technologies to deliver enhanced products, services, and customer engagement (digital offering). It requires creating a digital platform.
Here is a simple comparison
To know more, you can read these two research briefs from the MIT Center for Information Systems Research.