UA uses a session-based data model, focusing on sessions and page views, organized by source, medium, campaign, content, and keywords.
GA4 uses an event-based model, treating every interaction as an event, offering a detailed view of user behavior.
UA tracks users and activities using cookies, less effective when users switch devices.
GA4 uses multiple identifiers for tracking, unifying the user journey across devices.
GA4 has native cross-platform tracking, while UA requires customization for the same capability.
GA4 provides a flexible and comprehensive reporting system compared to UA's mostly predefined reports.
Although, GA4 also provides custmized reporting system that you can custimze own report based on events and parameters you want to analyze.
GA4 utilizes machine learning to predict future user actions and offer valuable insights, which is not available in UA.