Is there a difference?
Although some use these terms interchangeably, yes there is a difference.
In essence, digitisation is converting analog into digital, in other words converting something into bits and bytes.
Examples of digitisation are scanning paper documents into a PDF, converting vintage photos into digital photos, and even cassettes into mp3 formats.
Digitalisation, on the other hand, is the implementation of technology to enhance processes and models for more productivity, efficiency, and profitability within an organisation. Digitalisation may even rely on digitization.
Examples of digitalisation are using the cloud to store files, having a centralised database for customers, and setting up an online shop.