I don't understand much about swapping SIM cards in phones. I'm not sure how to determine which would work with which. I see that Boost has a Galaxy S2 phone. T-Mobile also has it.
Are the internals of each exactly the same?
If I unlock the Boost Galaxy S2, will I be able to use a T-Mobile SIM card use it on their network?'

I want to use T-Mobile because they have a plan that I like. I also have some gift cards for a place that sells the Boost Galaxy so I can get it cheaper than buying directly from T-Mobile.

Thank you very much.