Unit to buy medical masks invoice why the tax point of 13% and 1%?

Open 1% VAT invoice is small-scale taxpayers, open 13% VAT invoice is general taxpayers, small-scale taxpayers VAT levy rate of 3%, there is a reduction in the current year, but general taxpayers do not have a reduction. Specific documents: "Ministry of Finance? Announcement of the State Administration of Taxation on VAT Policies for Supporting Individual Industrial and Commercial Households in Resuming Work and Business (Ministry of Finance and State Administration of Taxation Announcement No. 13 of 2020). SAT Announcement No. 13 of 2020) From March 1 to May 31, 2020, for small-scale taxpayers of VAT in Hubei Province, VAT exemption is granted for taxable sales income to which the 3% levy rate applies; prepaid VAT items to which the 3% prepayment rate applies are suspended from prepayment of VAT. For small-scale VAT payers in other provinces, autonomous regions and municipalities directly under the Central Government, except for Hubei Province, the VAT is levied at a reduced rate of 1% on taxable sales income subject to the 3% levy rate; and the prepaid VAT items subject to the 3% pre-payment rate are subject to a reduced rate of 1% pre-payment of VAT. Ministry of Finance General Administration of Taxation Announcement No. 24 of 2020, "Ministry of Finance? Announcement of the State Administration of Taxation on the VAT Policies for Supporting Individual Industrial and Commercial Enterprises in Resuming Work and Resuming Business (Ministry of Finance? Announcement of the State Administration of Taxation No. 13 of 2020), the implementation period of the tax incentives stipulated in the Announcement is extended to December 31, 2020;