Is TM4C123 similar to Arduino? I'm currently studying embedded systems on eDx.
https://courses.edx.org/courses/UTAustinX/UT.6.01x/1T2014/info (must login to see)
http://users.ece.utexas.edu/~valvano/edX/index.html (don't need to login)
and I found out that TM4C123 is quite similar to Arduino.
but I haven't worked TM4C123 yet.(I ordered it and I'm waiting for it)
 I don't know much about it.
and it's not that popular as Arduino I guess.
so If anyone has used Tm4C123, please give me some information compared to Arduino.
The Tiva C LaunchPad is comparable to the Arduino Due in power and capabilities, but is incompatible with the stock Arduino ecosystem. It uses "BoosterPacks" rather than Shields, and Code Composer Studio (or other [some non-gratis] tools) instead of the Arduino IDE and libraries.

The Energia IDE is a port of the Arduino IDE and significantly simplifies configuration and programming Tiva C launchpads.

Beware of odd quirks with the Tiva C Launchpad board, such as the 0-ohm shunts that must be removed if you want all pins to be completely independent.