Time dummies in Panel Data

Hello all,

I have a general question about fixed effect estimation in Stata concerning time dummies. What is the difference between having one trend variable (1,2,3..T) and having T-1 dummy variables for each time period?
I have GDP growth one the left hand side and various independent variables on the right hand side. My dataset contains of 143 countries.I am using Stata 10.1 for Windows and areg for the fixed effect regression.

Thanks!