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8 means speed 8Mhz
A means Thin (1.0 mm) Plastic Gull Wing Quad Flat Package (TQFP)
I means Industrial (-40°C to 85°C)
U means Pb-free packaging alternative (includes the industrial temperature range, too)
Either AU or AI for you means the same thing : 44-lead TQFP package working in temperature range (-40°C to 85°C)