Form 16A reflects the amount that has been deducted at the time of making payment.
If you are receiving amount from 10 different sources and TDS has been deducted thereon, you would be issued 10 different Form 16A
Form 26AS is the amount which has been deposited with the govt. A single Form 26AS contains all the details of all the tax deducted.
Form 26AS reflects that the amount deducted and shown in Form 16A has actually been deposited with the Govt.
Moreover, you can only take credit of the amount shown in Form 26AS
Refer this article for more: https://www.charteredclub.com/form-26as/