Abundance is related to intangible things that serve your inner world. Seeking abundance then is about embracing love, peace, well-being, joy, gratitude and all the other attributes that create inner wealth.
Prosperity is related to tangible things that serve your outer world. Desiring prosperity is about finances, jobs, and all the things you gather into your space in life. This creates outer wealth.
We may seek prosperity without what we term "abundance," but it may turn out to be fickle because what we have to fight to get, we have to fight to keep.
If we strive for abundance first, then prosperity will come to us as we need it or desire it.