Firstly, Form 16-A is one of the two parts of Form 16. But in contrast to Form 16 which only entails salary income, Form 16-A includes TDS on salary as well. Moreover, all details from Form 16-A can be seen in Form 26AS. On the other hand, only details of TDS deducted by employer, from Form 16 can be viewed in Form 26 AS. Form 26AS is a form to file returns. However, you need both Form 16 and Form 16-A. It is so because, these certify TDS on salary.