macOS Catalina and macOS Big Sur are consecutive major releases that share app compatibility and similar user workflows, but they differ in system architecture, security model, and long-term support. This comparison explains their relationship, what changes between them, and how to decide whether to stay on Catalina or move to Big Sur based on your hardware, security needs, and app requirements. It focuses on enduring platform behavior, compatibility realities, and practical upgrade considerations rather than short-term news.
Relationship and release context
Catalina (released fall 2019) and Big Sur (released fall 2020) represent a major and an incremental macOS release, respectively. Big Sur adopts newer developer tools and builds on Catalina’s foundation while introducing a refined design and new privacy controls. Apple generally expects users on Catalina to be able to upgrade to Big Sur when supported, though not all Macs that run Catalina can run Big Sur due to firmware and hardware requirements. Understanding their relationship helps you plan updates, manage apps, and maintain security over time.
Architectural and system foundation differences
Both releases require macOS X 10.11 or later for initial install and share the same app model on Apple silicon; on Intel Macs the architectures diverge in important ways. Catalina enforces System Integrity Protection (SIP) and transitions 32-bit apps to 64-bit only, while Big Sur extends this with stronger signed-system-policy enforcement and additional kernel protections. Key architectural notes include:
- Big Sur mandates Apple silicon or Intel Macs with specific hardware features such as T2 or Apple processors for some capabilities.
- Catalina introduced 64-bit-only apps for many system components, and Big Sur expands this to more system processes.
- Secure Boot and verified boot chains are more rigorous in Big Sur on Apple silicon, affecting startup and updates.
Minimum hardware compatibility at release
| macOS version | Release year | General minimum hardware | Apple silicon requirement |
|---|---|---|---|
| Catalina | 2019 | Macs from 2012 or later; some models require 2015 or later | Not required; supported on Intel Macs |
| Big Sur | 2020 | Macs from 2013 or later for Intel; specific models for Apple silicon | Apple silicon Macs (M1, M2 series and later) |
Security, privacy, and verification model
Big Sur enhances the security foundations introduced in Catalina with more transparent privacy controls, stricter app notarization, and refined user consent flows. Notable security and privacy differences include:
- Big Sur adds more detailed location and camera usage indicators and finer app permission categories.
- System extensions and kernel extensions are more strictly controlled in Big Sur.
- Notarization requirements are broader in Big Sur, and users see more clarity around app origins and developer identity.
These changes are designed to reduce malware risk and increase user awareness, but they also raise minimum hardware and firmware expectations, which can affect compatibility on older Intel Macs.
App support, App Store, and third-party considerations
Most apps that work in Catalina continue to work in Big Sur, but developers may choose to update their apps to use new APIs and system features. Key points include:
- Big Sur enforces stricter code signing and notarization for apps, which can affect older or unupdated software.
- The App Store in Big Sur highlights more privacy details about apps before installation.
- If you rely on legacy 32-bit Intel-only software, Catalina may be the last macOS version that supports it; Big Sur removes remaining 32-bit app support entirely.
Update support, lifecycle, and upgrade guidance
Apple’s public update support policy means releases receive months of security updates after a newer major release. As of now, Catalina no longer receives major feature updates, while Big Sur continues to get periodic security and functionality updates. Consider these practical points when choosing to stay on Catalina or upgrade to Big Sur:
- Security: Big Sur includes newer mitigations and more rigorous verification, which can matter for high-security environments.
- Compatibility: Verify that your most-used apps have versions or update plans that support Big Sur, especially if they are currently 32-bit or rely on deprecated interfaces.
- Hardware: If your Mac relies on firmware updates available only for Catalina, staying put may reduce risk of boot issues.
- Features: Big Sur introduces redesigned notifications, Control Center, and Stage Manager on compatible hardware; these are not backported to Catalina.
User experience, interface, and workflow changes
Big Sur brings visible interface refinements such as new app icons, a centered Control Center, and transparent menu bars, which can affect visual workflows and third-party theming. Catalina follows the earlier design language and retains some legacy UI elements that some users prefer for familiarity. The shift to a flatter, more compact UI in Big Sur changes on-screen density and interaction patterns, so users who rely on specific layouts should verify window behavior after upgrading.
Reliability, stability, and upgrade readiness checklist
Before upgrading, evaluate your environment using an objective checklist that captures hardware, apps, and workflows:
- Confirm your Mac model is officially supported by Big Sur.
- Check each critical app for Big Sur-compatible versions or alternatives.
- Ensure firmware is current and that required updates were applied under Catalina.
- Back up important data and create a bootable installer or Time Machine snapshot.
- Test essential workflows in a non-production account when possible.
For organizations or users who depend on consistent behavior, staying on a mature release like Catalina until app and hardware requirements align with Big Sur can reduce disruption, even if that means planning eventual migration.