Broadly speaking, the two terms are similar. Whether one is "contributing" to the goal of carbon neutrality or "offsetting" one's carbon footprint, the idea is to fund carbon reduction or sequestration projects.
So far, the term "carbon contribution" has not been widely used, but it is now taking precedence over the term "carbon offset". In fact, it would be misleading to instill in individuals and professionals that we can fix our emissions by simply “offsetting” our actual emissions with hypothetical future absorption. Now, we need to reduce greenhouse gas emissions before we can offset residual emissions -- that is, we really can't avoid emissions.