Will this Product Work in a Mid 2010 Mac Pro 2.8GHz Quad Core Intel- And whats the difference between  Apple Memory Module 4GB 1333MHz DDR3 ECC SDRAM

Apple Memory Module 8GB 1066MHz DDR3 (PC3-8500) - 2x4GB SO-DIMMs

Apple Memory Module 8GB 1066MHz DDR3 (PC3-8500) - 2x4GB SO-DIMMs

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