Isaac Lab vs Isaac Sim
They are not alternatives; they are layers in the same stack. Isaac Sim is the simulator. Isaac Lab is the learning framework that runs on Isaac Sim. Here is what each does, when you need each, and where the older OmniIsaacGymEnvs and Isaac Orbit projects fit.
Updated June 5, 2026 · by Ugur Yekta
The short answer
Isaac Sim is a full physics-accurate robotics simulator built on Omniverse and OpenUSD. Isaac Lab is a unified framework for robot learning, RL and IL, that runs on top of Isaac Sim, with GPU-parallel environments and standard task suites. Most teams need both: Isaac Sim for simulation infrastructure, Isaac Lab for policy training.
Side-by-side comparison
| Isaac Sim NVIDIA's OpenUSD robotics simulator | Isaac Lab Unified learning framework on Isaac Sim | |
|---|---|---|
| What it is | Physics-accurate robotics simulator | Unified RL/IL framework on top of Isaac Sim |
| Layer in stack | Simulator (Omniverse Kit + PhysX 5) | Learning framework on Isaac Sim |
| Primary use | General simulation, digital twins, sensor sim, testing | Training RL / IL policies at scale on GPU |
| Asset format | OpenUSD (USDPhysics schemas) | OpenUSD via Isaac Sim; MJCF via MJX backend |
| GPU parallelism | Single-environment, RTX rendering | Thousands of parallel environments per GPU |
| Learning task suite | Not included | Manipulation, locomotion, mobile-base task suites included |
| Replaces | Isaac Gym (deprecated) | OmniIsaacGymEnvs + Isaac Orbit (merged into Isaac Lab) |
| Setup complexity | Install Omniverse + Isaac Sim (Linux/Windows, NVIDIA GPU) | Install Isaac Sim, then pip-install Isaac Lab |
| Best fit | Building scenes, sensor sim, digital twins, general simulation | Training and benchmarking RL/IL policies at scale |
Isaac Sim: the simulator
NVIDIA Isaac Sim is a physics-accurate robotics simulator built on the Omniverse Kit framework and PhysX 5. It runs on OpenUSD as its native format, with USDPhysics schemas (PhysicsRigidBodyAPI, PhysicsMassAPI, PhysicsCollisionAPI, PhysicsArticulationRootAPI) describing the physics. Isaac Sim provides RTX-accelerated sensor simulation (cameras, LiDAR, IMU, force sensors), scene composition, ROS 2 bridges, and a Python API for scripted control. It is the simulation infrastructure: if you need a robot in a physics-accurate world with realistic sensors, Isaac Sim is the runtime. It is not a learning framework on its own; it gives you the sim, not the training loop.
Isaac Lab: the learning framework
Isaac Lab is the unified learning framework for robot RL and IL on Isaac Sim. It replaces (and merges) two earlier projects: OmniIsaacGymEnvs (the original Isaac Sim RL environments) and Isaac Orbit (a higher-level abstraction). Isaac Lab provides GPU-parallel environments, thousands of robots stepping in parallel on a single GPU, plus standard task suites for manipulation, locomotion, and mobile-base navigation. It integrates with common RL libraries (rsl_rl, RL Games, Stable Baselines3, RLlib) and includes an MJX backend so you can run MuJoCo-style fast simulation when GPU parallelism dominates performance over RTX rendering. For training policies at sim-to-real-grade scale, Isaac Lab is the canonical NVIDIA tool.
When you need each (or both)
If you are simulating a scene to test a policy, build a digital twin, or render synthetic sensor data, you need Isaac Sim. If you are training a policy with reinforcement or imitation learning at scale, you need Isaac Lab, which means you also need Isaac Sim, because Isaac Lab runs on it. The legacy names still confuse people: OmniIsaacGymEnvs is replaced by Isaac Lab; Isaac Orbit was merged into Isaac Lab; the original Isaac Gym (no Omni-) is deprecated entirely. New work should start with Isaac Lab + Isaac Sim and ignore the older names. The boundary is clean once you see it: Isaac Sim is the world, Isaac Lab is the training loop that lives in it.
When to choose each
Isaac Sim
General robotics simulation, digital twins, sensor synthesis, OpenUSD scene composition, ROS 2 integration testing, and any workflow where physical-accuracy and rendering matter more than policy-training throughput.
Isaac Lab
Training RL or IL policies at scale, contact-rich manipulation, locomotion, and any task where GPU-parallel environment throughput dominates the workload. Always paired with Isaac Sim underneath.
Where Rigyd fits
Rigyd produces SimReady OpenUSD assets that drop into Isaac Sim scenes and Isaac Lab task suites without re-authoring. AI-estimated mass and friction land inside the typical domain-randomization band Isaac Lab tasks already wrap around values, so policies trained on Rigyd assets transfer like policies trained on hand-tuned assets.
Frequently asked questions
Is Isaac Lab a replacement for Isaac Sim?
No. Isaac Lab runs on top of Isaac Sim, Isaac Sim is the simulator, Isaac Lab is the learning framework that uses it. You install Isaac Sim first, then pip-install Isaac Lab on top of it.
Do I need both Isaac Sim and Isaac Lab?
If you are training RL/IL policies, yes, Isaac Lab is the framework that does the training, and it depends on Isaac Sim. If you are doing general robotics simulation, sensor sim, or digital twins without training a policy in-loop, Isaac Sim alone is fine.
What is the relationship to NVIDIA Omniverse?
Both Isaac Sim and Isaac Lab are built on Omniverse Kit, NVIDIA's OpenUSD-based platform. Omniverse provides the scene format, rendering, and extensions framework. Isaac Sim provides the robotics-specific extensions (sensor sim, ROS 2 bridges, articulation control), and Isaac Lab provides the learning framework on top.
Where do OmniIsaacGymEnvs and Isaac Orbit fit?
OmniIsaacGymEnvs was the original RL environment suite for Isaac Sim. Isaac Orbit was a higher-level abstraction NVIDIA built later. Both were merged into Isaac Lab in 2024, Isaac Lab is the unified, supported framework going forward, and the older projects should be considered legacy. The original Isaac Gym (without Omniverse) is fully deprecated.
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