promoted property makes schema variables visible for data 
segregation , distinguished property makes the variable 
visible within the orchestration.

There are two different ways in which you can
programmatically access an attribute or element in BizTalk,
they are called Distinguished Field and Promoted Property.
The main differences between them are summarized in the
table below.

Promoted properties can do everything and more than
distinguished fields, but this doesn't mean that
distinguished fields are less useful. Actually you should
prefer the use distinguished fields whenever possible:

	Distinguished Field	Promoted Property
Syntax	msgOrder.CustomerId	msgOrder(BookShop.CustomerId)
Access method	Using XPath in runtime.	Inserted in message
context during pipeline processing.
Can be accesses by	Only in code in orchestrations.	Both in
orchestration code and in the messaging configuration (e.g.
filters on send ports).
Storage	Only run-time access	A promoted property is stored
in the message context.
Constrained by message contents	Yes, only values within the
message may be accessed.	No, any type value can be promoted
in a pipeline (there is no need for the value to be
contained in the message).
Routable	No	Yes, as they are attached to the message context
they can be used for routing
Expensive (whatever that means)	No	Yes, even if they are
never used they are always read and inserted into the
message context. As the message is passed through the
MessageBox and Orchestration the context needs to be copied
and stored.
Visible in HAT	No	Yes
Size limit	Unlimited	Max 256 characters
XSD type support	More than prom.prop.	Less than dist.fields

Which one of these two ways to access elements/attributes in
a message should you choose? The answer will present itself
if you answer the following questions:

    * Do you need to route on the information in the
element/attribute?
    * Do you need to track the element/attribute?
    * Do you need to use information that can only be
dynamically created, i.e., it is not directly accessible in
the message.

If the answer to any of these questions is Yes, then you
need to use a promoted property. If the answers to all
questions are No, then you should use a distinguished field.

Depending on the type of solution you are creating you will
find that you use one of these more than the other.
Messaging solutions typically use promoted properties to
route incoming messages to the correct destination, there is
no need to use distinguished fields in messaging solutions
as you no way of accessing the value.

If you are building a solution containing orchestrations
that model business processes you will probably mainly use
distinguished fields. The reason for this is that you will
have less need for the routing capabilities of promoted
properties, and as it is less expensive from a performance
perspective to use distinguished fields you should prefer
these. In orchestrations you can use distinguished fields in
a number of ways; conditions for looping and decisions
shapes, expression shape and message assignment shape.

Basic rule for which to use would be: always use a
distinguished field, unless you have to route, track, or
correlate on the source content, then use a property (i.e.
promoted field).

Promoted properties can be accessed in Orchestrations, 
ports, pipelines, schemas.They Use server resources.
Distingished fields are light weight and can be accessed 
only in Orchestrations