Difference between alias foo bar and just foo = bar

Question

While learning ruby with tutorial on rubylearning i got to 'using alias' part of it. I cant understand what is the difference between using alias like in example:

def oldmtd  
  "old method"  
end  
alias newmtd oldmtd  
def oldmtd  
  "old improved method"  
end  
puts oldmtd  
puts newmtd

with output

old improved method
old method

and just assigning a new variable to this function, like:

def oldmtd  
  "old method"  
end  
newmtd = oldmtd  
def oldmtd  
  "old improved method"  
end  
puts oldmtd  
puts newmtd

with the same output:

old improved method
old method

Please, tell me what is actual difference and when it is correct to use 'alias'?

Answer 1

With newmtd = oldmtd you are not assigning a new variable to a function; you are assigning a variable to the result of a function, that is, a string. In Python terms: newmtd = oldmtd()