What's the difference between Kanban vs Lean Kanban? I noticed that Lean Kanban term appears quite frequently. I've tried to figure out what's the difference between Lean Kanban and Classic, but no success. Maybe someone dealt with both and could describe the difference and explain when to use what?

Lean is to Kanban as agile is to Scrum. One is a concrete implementation of the other.

Using the term "lean kanban" is just an attempt to court favour from Google/Bing for keyword density and is the result of copywriters rather than an actual thing.

All Kanban is Lean... But not all Lean is Kanban...