Did they remove some abilities?

[Adwel 1]

I havent played in over a year and thought id come back and finish the campaign and mess around with all the arcade options.

I feel like im not checking an option or something.  I remember being able to stealth kill from behind with Y button (xbox) where it chokes them out.  I also remember being able to stealth kill them in their sleep with a pillow.

Are these abilities actually removed for some reason?

 

 

[Adwel 1]

Another question, however unrelated, is what does the option in Arcade mode for World Layout actually do?  It offers "Line" or "Tree".  A descriptive tool tip is absent for this one.

What is the difference exactly?