There are differences between web browsers in case of their impact on battery life. The impact is affected by browser's performance settings, memory usage, CPU usage, usage of plugins and applications, background activities etc.
Some web browsers have a battery saver mode, with possibility to reduce performance to extend the battery life. Probably the most popular battery saver feature has Opera browser. Depending on your laptop, the feature might give you an extra hour of web browsing, so the impact on battery is quite significant.