It does not matter whether you work on third party payroll or company payroll.
ya, there is some difference in benefits which you would get by working in company's payroll.you should continue with offer acceptance,later you can grow yourself with more responsibilities.
and as it is your learning phase it would be a helpful for u.
Rest dont worry for contract of 1 year as per my understanding it would be extendable after completion of 1 year.
24th March 2018 From India, Pune