Carbon Offsetting is when a company invest in an environmental project not part of their value chain. The project generally is focused on compensating GHG that is already emitted into the atmosphere. It is an external compensation for emissions provide benefit for the purchaser and external provider.
Carbon Insetting is when companies invests in their own value chain making their businesses more sustainable. This requires designing a process that reduces carbon footprint from their upstream supply chain.
The difference between carbon offsets and insets is: Carbon Offsets is focused on doing less bad to the environment by minimizing the damage thru supporting 3rd party projects improving the environment.
Carbon Inset is focused on doing more good to the environment by changing company business model reducing emissions internally making the business more sustainable and future proof.