TS: Friends of the Earth vs. Greenpeace

Help me understand the differences between these two groups! Are there actual differences over specific issues here or does the difference lie rather in their presentation, the way they conduct their campaigns? Or do the differences lie more in the type of supporter each has? Who is the more effective of the two in your reckoning? Im quite interested how these perceptions vary on a global scale. Feel free to talk about other environmentally-minded NGOs here too!