To compare two strings without worrying about their case, one can call the String#casecmp? method.
This method returns true if the String passed in as an argument to the method is equal after Unicode case folding to the String the method is called upon, and false otherwise.
'ReD PaNda'.casecmp?('rEd PAnDa') # => true
'ReD PaNdas'.casecmp?('rEd PAnDa') # => false