Yes a tax stamp is different from a gun trust. A tax stamp is the actual proof of registration of your NFA Firearm. A gun trust is the applicant that is applying for a tax stamp and will become the owner of the NFA Firearm when the tax stamp is approved. You can apply for your tax stamp using the ATF Form 1, ATF Form 4 or ATF Form 5 depending the NFA Firearm that you are making or transferring. In summation a tax stamp stamp is the proof of registration of the NFA firearm and the gun trust is the applicant itself. Other applicant types include individual, corporations and other legal entities.