The main difference between UiPath Studio and UiPath StudioX is their target audience and functionality. UiPath Studio is aimed at technical users and allows for complex automation development, including the ability to split automations into smaller workflows that can be invoked from within other workflows. On the other hand, StudioX is designed for non-technical business users to automate tasks without writing code, and while it does allow for simpler workflows, it does not have the same depth of functionality as Studio for modularizing workflows.