Off the top of my head:
Utility value is the value placed on an ecosystem on whether it can provide any benefits towards human society (conservation of species in order to find medicines, new resources, new grounds for food production or as a habitat for a species that interacts beneficially towards humans). So pretty much keeping an environment to benefit humans but without causing damage. (Anyone want to refine this?)
Intrinsic value is the value placed on an ecosystem for it to simply exist. The main argument behind this is that all ecosystems are entitled to existing and that they should not have to suffer the fate that humanity has given them. This point is more for eco-people but is also taken into consideration in terms of developments and projects. In one example: Intertidal Wetlands at Bicentennial Park, they provide activities such as bushwalking or camping, are decent fitness venues, and are pleasant to look at. (I'm sure I got something wrong in here)
Hope that helps. I'll provide a better definition if you need it.