It is going to sound like it does. Live board mixes usually don't sound very good for a couple of reasons:
1. When you are mixing the show, you are mixing against the sound coming off the stage. The two combine to become the sound of the mix. Your recording will only consist of whate was sent through the PA. (If the guitars are really loud coming off the stage, they won't be very loud in the board mix)
2. When you are mixing the show, you are mixing against the sound of the PA in the room. Besides the obvious EQ'ing on the mains, the crossover settings and the number of amps for each frequency band will all play a roll in how the mix comes out. (If you have 5000 watts of sub and 1000 watts of mids and highs, the board mix will be thin to compensate for the PA)