Both have several, organic evidence is associated with biologicals. Biological evidence can be subjected to DNA analysis. Commonly at trial you will hear the phrase, "the science doesn't lie". If the defendants biological evidence was retrieved from the crime scene and it is shown that in fact it belongs to him, this is fairly concrete evidence that he perpetrated the crime.
A drawback to biologicals is the fact that some samples degradate or denature over time. So depending on when the evidence was collected and when it was tested will be a determining factor on its validity.
Inorganics can be useful in some of the same ways as biologicals ie, putting the suspect at the scene. A drawback to inorganics is that they are widely disbursed in the environment and always come up for challenge.