Structured data is organised and formatted in a way that it's easily searchable in relational databases, typically arranged in rows and columns like a spreadsheet. Examples include names, dates and customer data. On the other hand, unstructured data is not organised in a pre-defined manner or does not have a pre-defined data model, making it more difficult to collect, process, and analyse. It includes data like text files, emails, social media posts, video and audio files.