We will discuss difference between LG HOM-BOT 2.0 and 3.0 below.
LG HOM-BOT 3.0 vs 2.0
images from manufacturer

Both of the LG Hom Bot 2.0 and 3.0 include several models, for example, the VR6140 and VR6170 belong to 2.0 series, the VR6260 and VR6270 belong to 3.0 series.
The models within the same series have similar features and specs. But there are big differences between the 2.0 and 3.0.

Shape
The biggest difference is that the 3.0 series is in squarish shape instead of round shape on the 2.0 series.
The benefit of the squarish shape is that the robot can clean the corner and along wall better.

Dust Cup Capacity
The 3.0 uses a larger dust cup that has a capacity of 0.6L versus 0.4L on the 2.0 series.

Turbo Mode
The 3.0 features a Turbo Mode that cleans more powerfully than normal clean mode.

Side Brush
The side brushes on the 3.0 series is longer.

Cleaning Modes
The 3.0 adds a My Space Mode, Repeat Mode, and Learning Mode.
The MY SPACE cleaning mode allows the robot to clean the particular inner space you have selected.
If set to Repeat Mode, the Hom Bot will repeat the cleaning in progress unit it is short of battery power, then returns to the home base.
With the Learning Mode, the robot can memorize the cleaning environment, thus it will clean more efficiently and smartly.

Smart Diagnosis
The Hom Bot 3.0 adds a Smart Diagnosis feature that enables the robot to run a self diagnosis to check if there is abnormalities of its main parts.

HEPA Filter
The 3.0 uses HEPA (11) filter that is bigger than the HEPA (10) filter that is used on the 2.0 series.

Mopping
The Hom Bot 3.0 series uses a 2.5 times bigger mop.

If you know more difference between LG HOM-BOT(Roboking) 3.0 and 2.0, please share details below.