A few days ago, I heard about the Karel language. Also, I found some websites to learn (Stanford University,CodeHS). but it is not the same as the fanuc karel programming. That language is totally different. Can anyone explain that difference? which I learn? Is the Karel programming language applicable to all types of robots? or it is only applicable for fanuc only.Other brands have the same language programming method (like a computer or Python), or each robot constructs our new Karel language. if all or one karel learning is possible. Anyone give any resources for proper learning?
It's a simple case of accidental name duplication. The academics who created the "Stanford" Karel were not aware of Fanuc KAREL. The two have no connection (that I'm aware of).
Fanuc KAREL is brand-specific to Fanuc robots. Currently, every major industrial robot brand on the market has their own, brand-specific programming language. Recently, there have been some moves towards introducing Python or Java as an alternate language in some brands, but those are mostly all built on translation layers, and it's still very early days yet.
Autonomous Mobile Robots (AMRs) mostly tend to be black boxes internally, with REST API interfaces that can be accessed using whatever programming language you like, as long as it can parse strings correctly and communicate using TCP/IP sockets.
So it really depends on what type of robotics you want to get into. Personally, it's hard to go wrong knowing Python -- even if your robot can't run it, the basic rules of good programming remain the same, and Python is increasingly popular in a lot of contexts, including robot simulation. The open-source Robot Operating System (ROS) would be another good avenue of study, although that's a bit more on the robot "system-developer" end than on the robot "applications developer" end.
You might want to grab the free trial version (complexity-limited, not time-limited) of RoboDK, which is a really good entry point for understanding robot simulation on a budget (plus, Python scripting).