What is the difference between substance dualism and property dualism? Which position adequately defends dualism and why?

Substance dualism holds that there are two kinds of
substances or two states: The physical is all the material, matter.  The mental is
non-physical; it has no spatial extension; the mental, or mind (not to be confused with
brain, which is physical) exists but somewhere immaterial (abstract consciousness, soul,
etc.)  The mental state exists and can causally affect the physical world, but the
mental state is abstract and therefore external to the physical
world. 

Property dualism holds that there is only one type
of substance but two kinds of properties which inhere in that substance: mental and
physical.  There are different versions of PD but the general idea is that mental
properties, emerge, arise or are produced by/from physical properties.  Mental
properties can be reduced/explained by physical states or they cannot.  But, property
dualists do hold that there is an ontological difference between mental and physical
properties.  Examples of properties: redness, spherical.  These properties inhere in/on
physical properties but, isolated, what/where are they?  Thus, they have a quality
(property) that is ontologically different from the physical properties and states in
which they inhere.  Property dualists believe that the consciousness is a property which
inheres in a brain as red inheres in an apple. 

Analogously
speaking, if you think red can exist without inhering in anything then you are a
substance dualist; that is, red (consciousness) is not just a property.  It is an
abstract something that exists somewhere/somehow else and it can manifest through or
affect some physical thing.  If you think red needs the apple or emerges as a property
of it, then you are a property dualist.