How to check iphone 4 original or not ?

Actually i brought i phone 4 from Bangkok yesterday. i doubt its not a original i phone 4..

1. In box, they mentioned " iphone 4G " instead of iphone.
2. @Handset,
On apple site images: below "I phone 4" charecters one line space, where in my phone its specified 32GB.
3. Since in my phone i able to insert big sim (india model), where i read only micro sim accept iphone 4.

Please clarify me whether its fake or original..

sry if i posted this at wrong section.

thx, Sam