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.
How to guide and walk-through guide for the ATF Form 4 NFA Tax Stamp Application - Individual to Gun Trust Walk-Through Guide
ATF 5320.4 Application for Tax Paid Transfer and Registration of Firear...
How to guide and walk-through guide for the ATF Form 4 NFA Tax Stamp Application - Gun Trust to Gun Trust Walk-Through Guide
ATF 5320.4 Application for Tax Paid Transfer and Registration of Firearm...
The ATF 5320.23 is used when the applicant is a gun trust, corporation or other legal entity and is used to submit the personal information of the responsible persons within the gun trust, corporat...