Do all believers have the same spiritual gift and work in the same area for reward?
No. Not every believer has the same spiritual gift, nor do all work in the same area for reward. Yet every believer has something God has given that can be used as a gift, and that service can precipitate rewards.
Les explains that salvation is a gift of God, but once believers have received that gift, God logically expects them to go to work and work for reward. The idea is that we are not saved to sit, we are saved to serve, and this will be brought about at the behemoth seat of Christ. He also distinguishes rewards from crowns, saying the crowns—such as righteousness and life—should not be confused with rewards. Rewards are what believers receive as a result of what they have done in the body during this earthly sojourn. From Romans, Paul listed gifted men given to the church, showing that not everybody has the same gift and they are not all going to work in the same area for reward. But every believer has something. Regardless of who they are, old or young, each believer has something God has given that can be used as a gift, and it can in turn precipitate rewards.