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.
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.