Online term plans are on an average are 40% cheaper than the offline options. This is primarily because there is no intermediary involved in the process. You are directly connected to the company via their website, hence there is no room for any commission to agent.
Remember, insurance is based on the principle “uberrima fides”, meaning utmost good faith. Buying policy online is a transparent way of doing things, thus it becomes easier for insurance companies to understand about the customer.