What's The Difference Between Buy 1 Take 1 And 50% Off?

​In "Buy 1 Take 1", 
you pay the full price of the product 
and get an additional one for free. 
While in "50% Off", 
you get a similar deal 
but with an option to get 
just 1 of the products instead of 2. 

Buy 1 Take 1 Or 50% Off

​Let's say in "Buy 1 Take 1", 
you get 1 shirt for 200 
and get another 1 for free 
so you get both shirts for 200. 
While in "50% Off", 
you still get 2 shirts for 200 
with the option of getting only 1 for 100 
if you don't want both. 
In "Buy 1 Take 1", 
you have to pay 200 
and get 2 shirts and no option. 
Getting "50% Off" is a better deal 
if you don't have enough money.