From the Manufacturer

 
 Roomba 650Roomba 860Roomba 880Roomba 980
Self-Charging ✓ ✓ ✓ ✓
Multi-Room Navigation ✓ ✓
Entire Level Cleaning ✓
Recharge & Resume ✓
Scheduling ✓ ✓ ✓ ✓
Tangle-Free Debris Extractors ✓ ✓ ✓
iRobot HOME App ✓
3-Stage Cleaning System ✓ ✓ ✓ ✓
AeroForce 3-Stage Cleaning System ✓ ✓ ✓
Carpet Boost ✓