What is the difference between parts injected in PVC and parts Injected in ABS. I am interested in the structural properties that can give both materials. Is better to use ABS in injected parts that will be used as structural positions or will be used as a part of an assembly.

I think you will be well advised to discuss your particular requirements with your resin supplier or, perhaps, with your injection molder. They can offer advice to address your specific design and use parameters.
I think both ABS and PVC are used in similar applications and there must be reasons that one is chosen over the other. Get advice from those who make these choices.