Samsung Galaxy S4 & Samsung Note 2 use the same SIM card (Micro SIM Card)
In the good old days there is only one kind of SIM card (Mini SIM card). Mobile phone users don’t need to worry about the size of the SIM card. All changed after Apple first introduce Micro SIM card with it’s popular IPhone 4 and Samsung follow suite and use the same Micro SIM card in the flagship product Samsung Galaxy 3, Samsung Galaxy 4, Samsung Galaxy Note 2 etc.
Mini SIM is the normal one, which is in IPhone 3 and all the other mobile phones.
List of the SIM card used by popular Samsung Phone (Samsung Galaxy S3, Samsung Galaxy S4, Samsung Galaxy Note 2)
Here is how the SIM cards look like.
Size Specification of Mini Micro Nano SIM Cards
SIM Card adpaters(Nano to Micro, Micro to Normal)